Part of the multiplier is that they enjoy second-mover benefits.

The US buys a lot of very expensive first-of-its kind defense bric-a-brac. The rest of the world-- both foes and allies-- can ride on this expenditure.

1. They can watch what we buy that doesn't work and skip it. 2. They don't have to lead the way. For the price of one nth-generation tank/plane/missile, they can buy several previous-generation models and zerg rush. 3. When they're ready to make their cherry-picked decisions, it's a few years down the road and overall manufacturing technology-- from semiconductor processes to materials tech-- is a little further along, so building even largely the same unit will be cheaper.