That’s the coupons for American weaponry. The money mostly has to be spent to buy American weaponry, which has built up this dependence on us for certain weapons that we very much could use for leverage but mostly have refused to do (outside of the recent big bomb pause).
Assuming this is just another mistake (likely), it seems like since Russian arms sometimes end up hitting NATO soil, that the reasonable course of self-defense is to extend their air defenses and shoot down arms that come near their territory. You can’t know that the drone will go off target until it does, so you just have to shoot down anything heading in the general direction, even if it’s likely targeting Ukraine.