The good news is that World War III hasn't happened and no nuclear weapons have been used in anger on Earth. The bad news is that people haven't outgrown warfare. With multiple great powers, new arenas for conflict, and no global policeman walking the beat, small wars can easily turn big. Even big wars are less destructive to individual people, though. The poorest nations now have access to smart weapons, and if they want to take out their enemies in surgical fashion, they can do so. On the other hand, new weapons such as target-seeking nano have made genocide much more practical. Fortunately, most nations recognize that such weapons are beyond the pale. Unfortunately, 'most' is not 'all'.

An early 21st-century revolution in military affairs was the spread of highly realistic world-modeling simulations. The United States and its close allies had long used human intelligence, satellites, and microbots to create realistic simulations of nearly everywhere, but in 2100, just about everyone has them. The main difference is the level of fidelity. Those used my major powers are hyper-realistic, allowing the creation of armies of 'virtual veterans' whose simulated combat experience is very close to the real thing. This technology is also synergistic with the civilian entertainment industry, funding research that led to 'slinky' interactive media. Many modern military simulations are so sophisticated that soldiers may occasionally be uncertain whether a particular mission is a real operation or an interactive simulation.

Armored fighting vehicles remain the battlefield arm of decision. Most are cybershells. Some look like normal tanks or armored cars, but vehicles for urban and space habitat warfare can resemble multilegged insects or snakes. Larger cybershells mount electromagnetic (emag) cannon as their primary weapons, supplemented by point-defense turrets with lasers or emags to kill missiles and artillery shells. All have electronic warfare suites and are networked together, sometimes forming a gestalt mass-mind. The final defense is layers of nanocomposite armor. Bigger tanks carry multiple smaller vehicles, with expendable micro-air vehicles and spider-like 'dragoons' to hunt for ambushes and mines.

Infantry in Third and Fourth Wave nations are mainly humans or bioroids, due to the expense of putting SAI into a soldier-sized package. Their tasks are scouting close terrain (especially built-up areas), forward observation and target designation, urban warfare, peacekeeping, and special operations. Infantry always wear sealed body armor, and often use powered smartsuits or battlesuits for protection, mobility, and to lug heavier weapons and ammunition. Troops use virtual interfaces and augmented reality to synthesize tactical information and coordinate operations. Soldiers often have biomods to boost reflexes, diminish the effect of injuries, and banish fear and fatigue. The 2080s saw large-scale introduction of combat bioroids that had these abilities at birth. However, Fifth Wave powers are now replacing humans and bioroids with cybershells controlled by sapient infomorphs. This has led to a lot of surplus bioroids becoming available.

Conventional over-the-horizon artillery support is provided by rapid-fire, high-velocity electromagnetic cannon, as slower, indirect-fire rockets and missiles are vulnerable to point-defense weapons. Artillery rounds typically have satellite guidance or homing submunitions, though dumb shells are also used in intense electronic-warfare environments. Despite generally better aim, more powerful explosives, and lethal submunitions (including microbot warheads), artillery is less of a killer than in the past. This is due to most infantry being well armored and to very fast counter-battery responses. It's hard to get off a barrage before enemy sensors have tracked it back to its point of origin. As a result, more and more artillery trades some accuracy for fire on the move.

Logistics has been revolutionized by minifacturing. A truck can carry a 3D printer, allowing forward supply bases to manufacture spare parts, even weapons or ammunition - although for ammunition, conventional resupply is normally faster and more cost-effective. Expensive new 'cannibal nanokits' can even convert civilian or enemy equipment into friendly gear. Minifacturing has been a boon to unconventional warfare, allowing guerrilla forces and special-ops troops behind enemy lines to produce sophisticated weaponry rapidly instead of having to smuggle it in.

Command-and-control relies on human judgment supplemented by AIs. Combat and staff leaders, like their troops, usually have biomods, and are sometimes uploaded to transcend bodily limitations. While SAIs are not supposed to command troops, they fill many staff positions, especially in intelligence. It is often said that Fifth Wave military leaders are the most 'transhuman' individuals around.

Microbot cyberswarms are regular partners. Combat vehicles carry internal self-repair swarms, and swarms are also used for scouting, engineering, and medical operations. Microbot swarms are essential in urban warfare. Counterattacking cyberswarms often involves defense swarms or EMP munitions.

The wild blue yonder is not a good place to be. Lasers and electromag railguns can reach out and kill anything they can see. Survival requires stealth and low altitudes, and even then it's dicey. The majority of tactical aircraft are small, unmanned combat air vehicles (UCAVS) that can skim the ground at treetop or lower altitudes and pull 20- to 40-G evasive maneuvers when detected. Weapons are Gatling guns, electromag cannon, and short-range missiles. Human squadron leaders or command aircraft may fly behind the UCAVs to provide battle direction, in case jamming becomes intense or communications links are destroyed. Pilots have extensive biomods to prevent blackouts and reduce reaction time, and are often immersed in fluid-filled womb tanks to protect against high accelerations. Some craft are large enough to carry sizable airborne lasers; after the UCAVs have suppressed enemy antiaircraft lasers, they can orbit the battlefield and start killing enemy aircraft or missiles. Such aerial laser stations are also useful (in good weather) for precision ground strikes, best aimed by friendly observers on the ground.

Spacecraft and satellites provide strategic-strike capabilities, but hypersonic transatmospheric vehicles (TCAVs) are useful against lower-technology opposition. At Mach 5 to 15, they're easy to spot from thermal heating of the hull, but as long as there are no lasers overhead, they can provide rapid global strike and recon capabilities, launching missiles, smaller UCAVs, or even assault pods housing special-ops troops from well beyond the horizon with more precision than spacecraft, and adding their high speed to the punch of any kinetic weapons. Usually, the TCAVs go in only after space superiority is achieved.

Traditional paratroops are too vulnerable to use in this environment, but the ruggedness of some cybershell and microbot designs has brought a deadly new form of glider infantry into existence. A cybershell can be built to survive massive shocks. Stealthy bombers or transports launch silent, unpowered, and stealthy 2,000-lb. glide bombs from many miles away; they pop drogue chutes and land hard, but not hard enough to damage what's inside. Shock-absorbing cocoons open up and cat or dog-sized cybershells uncoil from compact shapes into lethal hunters.

The oceans remain an area for international conflict. Naval forces have even deployed off Earth: the United States and China operate small patrol forces on Mars and Titan, and conflicts between private navies of minisubs and aquatic robots are occurring beneath Europa's ice. The major revolution has been the development of supercavitating technology. A submarine, torpedo, or even gun shell can be designed to create a specially shaped bubble that vastly decreases water drag. The catch is that the object has to be going very fast for supercavitation to work - not a problem for underwater gun shells, but subs and torpedoes can normally sustain supercavitation for only a few minutes at a time. The payoff? The ability to sprint at 200+ mph underwater.

Modern surface warships still exist, but the oceans are becoming quieter; the Pacific War revealed that surface craft are significantly vulnerable to hypersonic missile strikes, orbital weapons, and supercavitating torpedoes, despite top-of-the-line vessels' fusion power plants and laser or electromag turrets. Modern warships have added their own underwater turrets for engaging subs and torpedoes, mounting blue-green lasers or guns firing supercavitating bullets and shells, although the range is quite limited and interception often depends on successful early warning.

Some powers have deployed high-speed attack subs armed with lasers, guns, and torpedoes, but the promary naval weapon is the nuclear-powered 'arsenal sub', which, while capable of sea control, is intended for land-attack operations. Its main weapons are dozens of launch tubes housing supercavitating torpedoes, stealthy cruise missiles, intelligent mines, and even small UCAV fighters, all of which the sub can launch while still submerged.

Not everyone can afford these supersubs. In the last war, the TSA fleet included cheap, concrete-hulled vessels that dispensed with conventional ballast tanks and used propellers to provide lift. Lurking on the sea floor, these vessels attacked with vertical-launch torpedoes.

Most nations' coastal defenses make conventional amphibious operations more difficult than ever, primarily due to the difficulty of surprise when every power possesses extensive space surveillance and unmanned submarine and aerial scouts. Amphibious raids are still performed, but mainly by submarines; a few powers have even built specialized submarine assault carriers, capable of deploying company-sized marine and special-ops units. These units include cybershells (many of them crab-sized or smaller), aquatic bioroids, and uplifted sea life. The need to attack or defend large surface and underwater habitats like Elandra poses an additional challenge, especially if they need to be taken intact.

Full-scale warfare is rare, though the sudden violence of the Pacific War convinced militaries of the need to continue to plan for it. Still, the majority of 22nd-century military actions are not targeted against the armed forces of another state. Instead, they include:

Aid to the Civil Power: Disaster relief and riot suppression.

Cadre Operations: Training allied troops. Usually performed by special-operations forces.

Deterrent and Security: Placing military forces in a threatened area to dissuade others from taking political or military action, or to be ready to act if a threat materializes.

Evacuation: The rapid removal of own-country nationals (such as diplomats, business people, or tourists), and sometimes others, from areas threatened by conflict or disaster.

International Counterterrorism: Targeting terrorists in space or other countries beyond the reach of national police forces.

International Law Enforcement: The suppression of crimes performed by nongovernmental powers beyond national borders.

Conflict between states can occur in operations other than war, if their interests collide. For example, one nation may insist on its right to chase terrorists or criminals fleeing into another nation's territory; the other may intercept the intruders. Conflicts can also occur over resource extraction in space, the oceans, and Antarctica - especially when some powers do not recognize international treaties governing those areas.

Third Wave: Infantry are human soldiers in partial body armor, with light automatic weapons equipped with laser and night-vision sights tied into head-up displays. All troops have helmet-mounted global positioning systems and secure communications links, forming a tactical network.

Fourth Wave: Infantry wear light, full-body nanocomposite armor or powered battlesuits. Troops are generally armed with multifunctional assault pods or battle rifles combining automatic weapons and smart grenade launchers. They are supported by remote 'teletroopers' and combat cybershells controlled by near-sapient AIs. Microbots and biomodified soldiers may be available.

Fifth Wave: Most infantry are autonomous cybershells. They are supported by bioroids or biomod humans with powered smartsuits or battlesuits for certain types of special operations. Electromags and lasers are common arms. Infantry munitions are often equipped with microbot-dispensing warheads.

The first armed spacecraft were 20th-century anti-satellite weapons tested during the Cold War. Serious deployment of space weapons did not occur until the 2030s, when growing rivalry between China and the United States led both powers to deploy laser and kinetic-energy weapons to protect vital satellites and orbital factories, and to strike air or surface targets with kinetic energy weapons that can de-orbit with devastating force. Fortunately for planetary forces, a vessel in a low orbit is only 'visible' for a short period, and one in a higher orbit is too far up to engage effectively.

The only space war so far was actually fought in Earth orbit, as China and the TSA blew each other's satellites and orbital factories apart at close range, and everyone else fought their own war with the lethal debris scattered about. However, the TSA's launch of dozens of robotic commerce raiders, and Duncanite hijackings of U.S. unmanned He-3 tankers, also made an impression.

In the 2090s, the maturation of the fusion drive allowed for rapid expansion of interplanetary trade and colonies, and also made deep-space warfare feasible. It was efficient enough to permit travel between planets in weeks rather than months, and powerful enough to allow spacecraft to carry payloads measured in the thousands of tons, whether mundane cargo or armor and weapons.

Most modern 'space dominance vehicles' are long and skinny, both to keep the radiation-spitting drive and crew quarters at opposite ends of the vessel and to present a minimal (but well-armored) front toward their enemies. However, an SDV cannot be armored everywhere and still accelerate quickly, and a long, thin SDV is vulnerable to attacks on its flanks. Thus, some spherical SDV designs have also been developed. Tacticians continue to debate the respective merits of 'spikes' and 'spheres' in different engagement types.

Encounters between the more common 'spikes' resemble, after a fashion, the tactics of Mediterranean galley warfare. A vessel attempts to outflank the enemy, so its armored nose points at the enemy's vulnerable side. This is nearly impossible for a single vessel to achieve in space, since a spacecraft can rotate independent of its direction of travel. The way to outflank an opponent is to outnumber him. A spacecraft caught between two separated enemies is faced with the choice of pointing its nose at one, leaving its less-armored sides or rear vulnerable to the other. To achieve or protect against flanking maneuvers, spacecraft that might operate alone often carry smaller fighters, usually unmanned, as well as broadside weapons batteries.

Space battles are fought with high-energy ultraviolet lasers and neutral-particle accelerator weapons. A multi-megawatt laser with a 3-yard focal array (the practical maximum in a robust weapon) can focus a beam on a dime-sized spot at a range of 5,000 miles with sufficient intensity to punch its way through a few inches of armor plate. At longer ranges, the beam begins to spread: the laser rapidly loses its ability to harm an armored hull, but can still disable exposed systems, such as laser irises and external heat radiators.

Neutral-particle accelerators can be even more effective, although only purpose-designed warcraft carry them. Particle beams do not have sufficient kinetic energy to blast through armor, but they can deliver devastating radiation damage that can fry electronics and incapacitate crew. Particle beams are another reason for the prevailing long-and-skinny spacecraft designs: powerful particle accelerators need to be hundreds of feet long.

Nuclear missiles are rare; there's still a stigma against going nuclear, and in any case, with no atmosphere to carry a blast wave or electromagnetic pulse, a direct hit or very near miss is needed to inflict damage. The exception is the X-ray laser warhead ('Teller mine'), a stand-off weapon which detonates a nuclear bomb and uses its radiation to energize multiple coherent X-ray beams. The bombs are kicked out a few miles from the firing craft by electromagnetic coilguns, coordinated by communications lasers, and directed using the main vessel's sensors, where they deliver a short-ranged but lethal one-time punch.

Small missiles cannot survive laser fire or mount drives efficient enough to intercept targets over long ranges. Robot fighters known as autonomous kill vehicles, or AKVs, have replaced them. A typical AKV masses upward of 50 tons, and can destroy small targets simply by ramming them at several miles per second. Not every opponent warrants such a sacrifice, so AKVs carry coilguns and munitions packages; instead of ramming a target, they make a close pass at a range of several miles and release a swarm of tungsten pellets, or launch a spread of Teller mines from a greater distance. Flights of AKVs often duel one another, as they jockey to outflank their respective mother ships and close for an X-ray laser or kinetic-energy kill.

A quirk of 22nd-century space warfare is the huge difference between weapon ranges and detection ranges. Even if a spacecraft drive is pointed away from a sensor, the energy signature of its power system and the relative 'warmth' of the vessel against the black of space means that (regardless of any stealth technology or electronic countermeasures) simple passive sensors can detect vessels at ranges in excess of 100,000 miles. Weapon ranges are far shorter, no more than a few thousand miles. Battles are often fought around points that each side needs to defend, attack, or resupply. Beyond Earth's orbit, small engagements between one to six major combatants are the rule, as even the greatest spacefaring powers are stretched thin.

Deep-space military forces are capable of effective operations many astronomical units from a base. Dozens of Earth nations (and unofficially, a few other entities) possess satellite weapons, transatmospheric fighters, and so on, but few have seen the need to invest in armed spacecraft capable of deep-space operations. The chief exceptions are the European Union, United States, and China, which believe their 'great power' status and extraterrestrial colonies require large space forces. Several other nations - e.g., Korea, India, Peru, Japan, and South Africa - have a small number of armed deep-space vessels. Many civilian vessels (especially those used by Duncanites) are also armed.

ESCA is the European Union's space defense agency. Its primary role is to defend the European Union from space attack, and it maintains a multinational orbital defense force of space defense platforms and AKVs. It also coordinates the space forces of the European Union nations. The three largest are:

Bundesraumwaffe: Germany's space force operates 10 SDVs and several smaller craft. German spacecraft make it their business to keep the peace around Luna and the Lagrange points. They lead most European Union humanitarian missions sent to troubled L5 habitats. They've been operating near Venus in response to reports of TSA activity.

Force Aerospatiale: France's space force operates nine SDVs and many smaller craft. Its deep-space defense commitments center on European Union installations in Earth-Luna space, but its special responsibility is the valuable EU presence on Mercury. In the past, the Force Aerospatiale has also seen long cruises that have taken SDVs near Europa, where a French-led astrobiological team is stationed. Some French generals and politicians believe the icy moon is overdue for another visit, to sort things out.

Royal Navy Space Service: A branch of the United Kingdom's Royal Navy, it evolved from the Submarine Service (who had necessary experience in nuclear reactors.) RNSS has eight SDVs and several other vessels. The RNSS has a close relationship with Vosper-Babbage and Hawking Industries, and often patrols UK-associated asteroid interests.

The areas of responsibility are not absolute. Joint forces are quite common; e.g., a Franco-German team operating in Lagrange 5.

PLAN-SF is China's space force. Its mission is to protect China from space attack, secure space superiority above China and Mars, protect Taiko Station, and protect China's other colonies and deep-space commerce. It is one of the few military forces with extensive experience in space warfare: its strike against TSA's orbital facilities has been studied by other powers. Since then, PLAN-SF has received the lion's share of China's military budget. It controls hundreds of space defense platforms and other weapons in Earth-Luna and Martian space, backed up by transatmospheric fighters and AKVs. In Earth orbit, PLAN-SF remains alert for any resurgence of TSA power and keeps an eye on the rival PRA.

The PLAN-SF Deep Space Fleet is a small but growing element of the PLA's power, tasked to protect interests on Mars, Mercury, and the Belt. Presently consisting of 30 SDVs and multiple smaller vessels, the Deep Space Fleet's homeport is at Phobos, with smaller bases scattered at military and corporate outposts and colonies through the solar system. The Deep Space Fleet saw limited action against TSA raiders in the Pacific War. It has since performed enforcement actions against suspected and actual Martian Triad and Trojan Mafia installations in the asteroids, and maintained 'freedom of navigation' patrols aimed at keeping a wary eye on ESCA and USAF operations in the inner system.

In 2037, the USAF secured a hard-fought victory over its most dangerous opponent and achieved control of deep space. The battlefield was Washington; the enemy was the nascent United States Space Force. As a result, it is the USAF alone that operates American military spacecraft. Collateral damage was the decision to make the Army's 82nd Spaceborne Division (rather than the Marines) America's prime 'space infantry' formation.

The USAF presently has two branches: Aerospace Command and Deep Space Command. Aerospace Command handles operations on Earth and in Earth orbit, while Deep Space Command handles everything beyond. Deep Space Command controls four Space Wings (the 30th, 90th, 91st, and 341st), each with a half-dozen SDVs and various support and transport vessels. Two are based in Earth-Lunar space, one in Mars orbit, and one at Rhea.

1. People's Liberation Army. Much of China's land army is still a Third to Fourth Wave force, but its best is very good indeed, and has been blooded in recent combat with the TSA.

2. European Union. The combined military forces of the European Union surpass those of China in technology and rival it in size, but lack combat experience. E.U. forces have intervened repeatedly in Africa and Lagrange 5, but usually to prop up friendly governments or perform humanitarian missions.

3. United States. The United States maintains a very powerful navy and effective aerospace and deep-space forces, although the U.S. Army is much smaller and far less 'heavy'. Its current strategic bugaboos are Peru (a bastion of nanosocialism) and China (a rival in space and on the oceans).

4. India. Its forces rival China's in numbers, and include some excellent units with long military traditions. Most are still Third Wave, but it has a hard core of Fourth Wave units, including some elite bioroid troops.

5. Pacific Rim Alliance. The combined military forces of Japan, Korea, and Australia are well equipped and trained, and in recent decades have had considerable combat experience. Their emphasis is on naval, aerospace, and special operations forces, although Korea maintains a large land army as well. Fears of TSA nanoweapons have diverted large budgets to 'active shield' civil defense.

6. Transpacific Alliance. The TSA's military forces are still recovering from the Pacific War and sanctions. Most are well equipped for internal security but lack offensive potential. Exceptions are Indonesia's naval, air, and marine forces, as well as Peru's ground and infowar troops, which have gained a fair degree of expertise as volunteers in 'conflicts of information liberation' worldwide.

Other nations with sizable or aggressive forces include Russia, the Islamic Caliphate, Pakistan, Brazil, Israel, South Africa, and Kazakstan.

Anyone can load troops into a spaceship and take them somewhere. Spaceborne forces are ground troops who have been specifically trained to launch attacks from space on defended habitats, moons, or planets. This requires specialized equipment, doctrine, and training for operations in multiple, widely diverse extraterrestrial environments, in close coordination with friendly space forces. As a result, there are only a few truly spaceborne forces. Examples include:

The former U.S. Army's 82nd Airborne Division has battle honors stretching back to WWII. Most of the infantry in the 82nd are cybershells (a mix of ghosts, shadows, and sapient AIs, all of whom are backed up on Earth, just in case they end up dead.) Their most recent combat experience was the suppression of the helium pirates of Hyperion. The 82nd has three brigades: in the Saturn system, on Mars, and in and around Earth. In operations other than war, it often deploys in conjunction with Special Forces personnel, who (unlike the cybershells of the 82nd) are mainly humans and bioroids.

The Foreign Legion is a professional fighting force with a proud tradition dating back to 1831. Legionnaires are famous for their esprit de corps: men of action, brave in combat, sharing close bonds of comradeship. Their motto is Legio Patra Nostra: the Legion is our homeland. They vow never to abandon a comrade, alive or dead, on the battlefield. The Legion is unique in that it accepts volunteers from any nation, model, or species who can meet its standards, and allows them to join under an assumed name. As such, people will often enlist to escape a troubled past (though the Legion does not accept criminals) or seek adventure. Officers are French, but more than half the enlisted personnel come from other nations. After completing three years' service, recruits may be granted French (and European Union) citizenship.

The 2e Regiment Etranger Spatial is the Legion unit trained for spaceborne operations. It is experienced in low-gravity vacuum operations on Mercury and in microgravity assaults on orbital factories and L5 colonies. The legion is a mix of cybershell troops and battlesuited humans and bioroids.

China's space mobile infantry, the 67th SID, saw some action during the Pacific War, although the heaviest fighting was on the ground. It consists of three quanto ('fist') rapid-reaction brigades: one based at Rust China on Mars, one on Taiko Station (normally for training and refitting), and one divided into smaller units stationed on other Chinese installations and spacecraft throughout the system. In addition to assault tasks, they provide security at Chinese spaceports and major space stations. Still largely a Fourth Wave military, the 67th uses battlesuited bioroids and low-sapient cybershells rather than the self-aware weapons deployed by the U.S. and E.U. Service in the 67th is one way for a bioroid to obtain high status in Chinese society.

Commachio Group's responsibility for protecting British oil rigs was extended in the 2040s to the United Kingdom's near-earth-orbit asteroid-mining operations. As the largely British-owned Vosper-Babbage corporation expanded into the Main Belt, its mission has further extended to protecting the lives and property of Hir Majesty's subjects at Aletheia Station and elsewhere. The Royal Marines (Commachio Group) are a modern force, but use more battlesuited humans and fewer cybershells than the U.S. Army. They are specialists in assaulting and defending asteroid installations, and are considered one of the finest counterterrorist and hostage-rescue units in the solar system.