Predicting which five weapons will have the greatest impact on the future of combat is a problematic endeavor, as the nature of warfare itself is fluid and constantly changing. A system that could be a game-changer in a major confrontation between two conventional forces—say, China and the United States—could be of little utility in an asymmetrical scenario pitting forces in an urban theater (e.g., Israeli forces confronting Palestinian guerrillas in Gaza or Lebanese Hezbollah in the suburbs of Beirut).

The world’s best fifth-generation stealth combat aircraft might be a game-changer in some contexts, but its tremendous speed and inability to linger makes it unsuitable to detect and target small units of freedom fighters operating in a city, not to mention that using such platforms to kill a few irregular soldiers carrying AK-47s is hardly cost effective. Special forces equipped with hyperstealth armor and light assault rifles firing “intelligent” small-caliber ammunition would be much more effective, and presumably much cheaper.

Another challenging aspect is choosing how we define revolution in the context of weapons development. Do we quantify impact using the yardstick of destructiveness and casualty rates alone? Or conversely, by a weapon’s ability to achieve a belligerent’s objectives while minimizing the cost in human lives? What of a “weapon” that obviates kinetic warfare altogether, perhaps by preemptively disabling an opponent’s ability to conduct military operations?

Keeping in mind the scenario-contingent nature of warfare, we can nevertheless try to establish a list of weapons systems, most of which are already in the development stage, that will, if only for a brief instant, change the nature of warfare. By trying to strike a balance between conventional warfare and irregular operations, our list is inherently incomplete but shows trends in the forms of warfare that are likely to affect our world for decades to come.

5. ‘Hyper Stealth’ or ‘Quantum Stealth’

Using naturally occurring metamaterials, scientists have been designing lightwave-bending materials that can greatly reduce the thermal and visible signatures of a target. The science behind it is relatively straightforward, though skeptics remain unconvinced and say they will believe it when they don’t see it: The “adaptive camouflage” renders what lies behind the object wearing the material by bending the light around it.

The military implications of such developments are self-evident, as “invisibility cloaks” would make it possible for fighters—from ordinary soldiers to special forces—to operate in enemy territory undetected, or at least buy them enough time to take the initiative. Such capabilities would reduce the risk of casualties during military operations while increasing the ability to launch surgical and surprise attacks against an opponent, or conduct sabotage and assassination.

A Canadian firm has reportedly demonstrated the material to two command groups in the U.S. military and two groups in the Canadian military, as well as to federal counterterrorism teams.

Of course, this technology would also have a serious impact on operations should it become available to nonstate actors like guerrilla forces and terrorist groups.

4. Electromagnetic Rail Guns

EM rail gun launchers use a magnetic field rather than chemical propellants (e.g., gunpowder or fuel) to thrust a projectile at long range and at velocities of 4,500 mph to 5,600 mph. Technology under development has demonstrated the ability to propel a projectile at a distance of 100 nautical miles using 32 megajoules.

The extended velocity and range of EM rail guns provides several benefits both in offensive and defensive terms, from precision strikes that can counter even the most advanced area defense systems to air defense against incoming targets. Another advantage of this technology is that it eliminates the need to store the hazardous high explosives and flammable materials necessary to launch conventional projectiles.

A naval EM rail gun system has been in development since 2005 by the U.S. Office of Naval Research. The current phase of the project, initiated in 2012, seeks to demonstrate sustained fire, or “rep-rate” capability.

The U.S. Navy hopes to eventually extend the range of EM rail guns to 200 nautical miles using 64 mega-joules, but as a single shot would require a stunning 6 million amps (bigger than the currents that cause the auroras), it’ll be years before scientists find a way to develop capacitors that can generate such energy, or gun materials that will not be shredded to pieces at every shot.

Not to be bested, the U.S. Army has been developing its own version of the EM rail gun. China is also rumored to be working on its own version, with satellite imagery emerging in late 2010 suggesting ongoing tests at an armor and artillery range near Baotou, in the Inner Mongolia Autonomous Region.

3. Space Weapons

Despite international pressure against the weaponization of space, major countries continue to explore technologies that would turn the sky above us into the next battleground. The possibilities are as limitless as they are outlandish, from moon-based missile launchers to systems that would capture and redirect asteroids towards a target on the surface of the Earth. Evidently, not all scenarios are technically feasible and will forever remain the stuff of science-fiction novels. But some breakthroughs are within the grasp of current science and would have a deep impact on the nature of warfare as we know it.

One possibility is the arming of space orbiters with nuclear or non-nuclear electromagnetic pulse (EMP) weapons. By detonating a satellite-launched EMP weapon at a high altitude, a belligerent could initiate a decapitation attack against an enemy’s electrical grids, satellites, as well as the command, control, communications, computers, intelligence, surveillance and reconnaissance (C4ISR) architecture that are necessary to conduct military operations. Depending on the size of the EMP weapon utilized, the attack could blanket an entire country, or be more surgical, targeting an area of operations. An “assassin’s mace” weapon of this type could theoretically end war before a single shot is fired—at least against a heavily information-reliant adversary such as the U.S. (much less so against, say, the Taliban or Hamas).

EMP weapons fired from lower-altitude platforms or via land-based missile systems (e.g., ICBMs) are vulnerable to intercepts or preemptive strikes. Satellite-mounted EMP weapons, on the other hand, would be beyond the reach of most countries, except those with ground- or air-to-space-based antisatellite capability or space-based weaponized orbiters. Furthermore, the reaction time to a space-based blackout attack would be much shorter, which diminishes the ability of a targeted country to intercept the EMP weapon.

Another technology, interest in which has waxed and waned over the decades, is the use of high-energy space-based lasers (SBL) to target ballistic missiles fired by an enemy during the boost phase (known as “boost-phase intercept,” or BPI). The advantage of BPI is that the attempt to deactivate a ballistic missile occurs during its slowest phase, thus making a successful intercept likelier.

Unlike the theater defense systems currently used for BPI (e.g. Aegis), which must be deployed close to enemy territory, space-based laser platforms can operate at altitudes that, as discussed above, are well beyond the ability of the targeted country to shoot down or deactivate prior to a launch. As more countries and “rogue states” acquire the means to deliver long-range—and possibly nuclear—ballistic missiles, interest in SBL interceptors, and the willingness to fund such costly programs, will likely grow. However, challenges remain in developing chemical megawatt-laser systems for orbiters.

2. Hypersonic Cruise Missiles and ‘Prompt Global Strike’

Had hypersonic cruise missiles existed in the mid-1990s, the U.S. might have rid itself of Al Qaeda leader Osama bin Laden much earlier than it did, and would have accomplished the feat in Afghanistan rather than in Pakistan.

With their ability to accurately deliver warheads over long distances, cruise missiles have had an extraordinary impact on modern warfare. But in an age where minutes can make a difference between defeat and victory, they tend to be too slow. It took eighty minutes for land-attack cruise missiles (LACM) launched from U.S. ships in the Arabian Sea to reach Al Qaeda training camps in Afghanistan in 1998 following the terrorist attacks against U.S. embassies in Kenya and Tanzania. Using hypersonic missiles cruising at speeds of Mach 5+, the same targets would have been reached within as little as 12 minutes, short enough to act on intelligence which had placed the terrorist mastermind at the location.

The desire to be able to strike anywhere, and to do so quickly, has led to the creation of a program known as “prompt global strike,” which the U.S. military initiated in 2001. Efforts have centered on the X-51A hypersonic cruise vehicle (HCV) under a consortium involving the U.S. Air Force, Boeing, the Defense Advanced Research Projects Agency (DARPA), the National Aeronautic and Space Administration, Pratt & Whitney Rocketdyne, and the USAF Research Laboratory’s Propulsion Directorate. Russia, China and India have made strides in developing the technology to achieve similar feats using conventional warheads, leading some defense analysts to warn of a looming global strike arms race.

The U.S. Navy is now reportedly exploring the possibility of developing submarine-launched hypersonic missiles.

As the 1998 example shows, global strike can serve multiple purposes, from decapitation attacks against heads of state, command-and-control systems and other high-value targets to surgical attacks against mobile terrorist groups under short timeframes offered by on-the-ground actionable intelligence. The extraordinary speeds achieved by hypersonic cruise missiles and the terrain-hugging nature of cruise missiles, meanwhile, will pose additional challenges in efforts to intercept them using existing air-defense systems, thus giving them an extra advantage in conventional-warfare scenarios.

1. ‘Sentient’ Unmanned Vehicles

Perhaps the single-most important development in the defense industry in the past decade is the emergence of unmanned vehicles. As the technology evolves, drones, as they are often called, are quickly taking over duties that have traditionally been the remit of human beings. Such has been their rise that some commentators have argued that unmanned aerial vehicles (UAV) could one day render human pilots obsolete.

But today’s drones, from bomb-removal buggies to undersea mini-subs, from ship-based surveillance helicopters to high-altitude assassination platforms, remain dumb and for the most part require a modicum of human intervention. Not only are most platforms piloted remotely by human beings (though with increasing automation), but key mission elements, such as target acquisition and the decision to fire a Hellfire missile at a target, continue to necessitate human supervision.

This could soon change as scientists push the boundaries of artificial intelligence, which could one day open the door to drones that make independent “decisions” that have life and death implications. Of course, unmanned vehicles, or robots in general, are not intelligent in the human sense of the word, nor can they be said to be sentient. But advances in computing power are giving machines greater situational awareness and adaptability. As those capabilities continue to improve, drones could one day become “fire-and-forget” weapons, with much greater attention spans and durability than human beings, capable of lingering over a target for several hours and making split-second decisions to strike when an opportunity occurs. Moreover, the incentives for giving combat roles to machines and endowing them with life-and-death decisions will continue to increase as the costs associated with training and retaining soldiers continue to rise (another disadvantage of using soldiers: they have grieving families and loved ones).

Giving robots license to kill is only the logical next step in the increasingly videogame-like nature of warfare. Their deployment adds yet another a layer of distance between the perpetrator of violence and the victim, which lowers the psychological threshold for using force. Once the decision is made to give drones combat duty, the incentive will be to make them as “free” as possible, as the side that acts the quickest, with the least decision chokepoints and human input, will likely prevail in a confrontation.

J. Michael Cole is a Taipei-based journalist, a Senior Fellow at the China Policy Institute University of Nottingham, a graduate in War Studies from the Royal Military College of Canada and a former analyst at the Canadian Security Intelligence Service.

Editor's Note: This piece first appeared in February of this year. It is being recirculated due to reader interest.