In 2019, the world was shocked when a five kiloton nuclear warhead was detonated in the middle of Beijing. While the Chinese mobilised themselves for a massive campaign of retaliation against the Global Liberation Army, protests by anti-nuclear activists around the world more than doubled and fears of nuclear war spiked to all high levels.
In most of the world, the response to this by governments was to promise to make several small reductions to their nuclear arsenal and tighten security procedures for them, while outright rejecting the possibility of completely phasing out nuclear weapons.
In the United States, however, things were somewhat different. While the Chinese started employing nuclear weapons liberally in its campaign against the GLA, the incumbent US President promised to greatly reduce the American nuclear arsenal over the next few years. The reason for him doing so was revealed a few months later, when the United States publicly unveiled the newly revitalised Strategic Defense Initiative (initially the brainchild of Ronald Reagan in the 1980s to put an end to the MAD doctrine), which had been in development for several years.
The new SDI was a multi-layered system, employing ground based Patriot missiles, orbit based kinetic interceptors, and airborne and surface based chemical lasers to intercept any ballistic missiles calculated to be on a trajectory bound for the continental United States. The centrepiece of the new SDI was the 'Particle Cannon Uplink Network'; a system of surface based installations and orbit based reflector satellites, to be the first line of defence against any ICBM attack.
In 2025, however, the Strategic Defense Initiative proved to be far more than just a defensive system, when Chinese general Ismail Khan defected to the GLA. The United States subsequently responded by employing a Particle Cannon installation to wipe out the rogue general's forces and his stockpile of nuclear weaponry. Subsequently, the US military would go on to employ the Particle Cannon network against the GLA on several occasions, though the system would be turned against them in 2027, when the GLA managed to hijack a supposedly secure Particle Cannon installation and use it to destroy the USS 'Ronald Reagan'.
While nowhere nearly as destructive as the nuclear weapons that it replaces, the Particle Cannon is a precise and powerful system, capable of efficiently eliminating high value targets with a minimum collateral damage.