In following the history of this, better information could be available by converting nominal dollars to real dollars, discounting for inflation or vice versa. When Bush left office, this was about $$800+ billion. Keep in mind that they added something toward $500 billion for Homeland Security and related items. Obama was able to bang down the first number to around $600+.
David Stockman, Reagan's young budget director and conscientious objector, noted that the so-called end of the Cold War did not evoke any disarmament -- or therefore a reduction in defense spending. Toward end of Clinton's term or at beginning of Bush's, it was something around $300+ billion.
Of course, the Cold War never really ended. Every conflict since beginning of Commonwealth of Independent States had been a Cold War hot-spot or region. For instance, Bosnia is within a region including Greece, where the US had defeated a communist insurgency without inserting troops. Iran had history of the Mossadegh coup, the hostages and drifting toward Russia. Iraq's Saddam had been a CIA asset which apparently drifted away from their control. Afghanistan -- well, the Russians themselves made a version in the "Platoon" or "Full Metal Jacket" genre. Then there's that criminal regime that was probably tutored more than a century ago by Japanese militarism or fascism. the subject of Halberstam's "The Coldest Winter."
We got some winks from Boris Yeltsin, but the Russians never got anything but "free-market promoters" -- Republicans -- who gave lectures. Nothing at all like a Marshall Plan. Blame Bush? Or blame Clinton? Clinton had his Willie in a vise. That whole decade was a distraction of nonsense.
Never trust a Republican to lecture anyone about rich men and free markets. Why do you think the Russians descended into an oligarchic kleptocracy?
Reducing the risk of war and reducing the cost of arms and arms races would take a tremendous burden from human shoulders.
The space-alien Trumpies want to throw money at weapons systems. They think that by controlling costs and choosing conflicts more carefully, we're not practicing readiness. They have a totally tribal view of the world, as if the collective tendencies too long in history cannot be themselves controlled, so let's be tribal, destructive, and wasteful. With peace through superior fire power, you also have a self-defeating cost factor in arms races. And arms races often lead to the use of arms.