Adam Hebert, executive editor of the Air Force Association’s house magazine, wrote an interesting piece in the July issue about the history of MIRVed ICBMs. He notes that the landmark SALT treaties had the opposite of their intended effect because they restricted only the number of launchers, not warheads—drastically increasing the desire for each side to MIRV their treaty-limited number of launch platforms.
Arms negotiator Paul C. Warnke memorably, and mistakenly, compared the superpowers to “apes on a treadmill,” with both “jogging in tandem on a treadmill to nowhere.” There was only one ape, though. Former Defense Secretary Harold Brown had it right when he said, “When we build, they build; when we stop building, they build.”
According to Natural Resources Defense Council estimates, the US and Soviet Union in 1975 each had roughly 2,200 warheads atop their ICBMs.
Over the next five years, the US total didn’t change, but Moscow more than doubled its MIRV force, winding up with 5,630 warheads fitted to its 1,400 or so land-based missiles. A huge number of these—more than 3,000 warheads—were found on the monster, 10-warhead SS-18 missiles. The Soviets had 308 of them.
— Hebert, Adam. “Issue Brief: The Rise and Semi-Fall of MIRV.” Air Force magazine, July 2010. [Emphasis mine]
Although we enjoy considerably less tension in relations between the great powers today, the old dynamic is still at work. While the United States has agreed to de-MIRV its entire Minuteman III inventory (and currently has about 550 warheads aboard 450 launchers), Russia maintains an inventory of 1,100 warheads aboard its 331 ICBMs.