Comments by Treasury Secretary Yellen and President Biden about “paying for two wars” has attracted some chatter. For example, Adam Tooze just wrote an article on it. As Tooze notes, saying that America is paying for two wars is a particularly bad framing for support for Ukraine and Israel. A good portion of United States aid is shipping “obsolete” weaponry (admittedly not as obsolete as Russian 1950s era equipment that is showing up on the front line), the offloading of which saves the United States the expenditures associated with decommissioning it. The United States is not going to have combat personnel on the ground under most plausible scenarios, and so the usual disruptive effects of a war are not present for the United States.
Yes, I think that orthodox economics is mostly used for post hoc rationalization of political decisions already taken.