A Different '78:
The Vietnam War ended in 1973 to an anonymously deployed bacterial weapon, killing most life in the country including thousands of U.S. soldiers and Soviet interests. The devastation was shocking to both sides, and nuclear war seemed unavoidable -- until a breakthrough in anti-nuclear weaponry led to the creation of the Anti Ballistic Missile System in Britain, which was quickly stolen and implemented around the world.
The ABMS, while initially a miracle, has given both sides reason to expand the development of alternate weapons for the war that both sides are set on avoiding; by way of totally eliminating the other side without having to resort to a costly conventional war. Little by little the ethical restrictions on weapon research are chipped away, and each day the world inches closer to devastation.
Spies are the big players in this costly game, fighting an endless tug-of-war of sabotage and espionage -- and each year they're being outfitted with more advanced gadgets to aid in their invisible war.
Remember that despite the grim setting, it is by no means grounded in reality. Get creative with your characters and gadgets!