We’ve chosen to spend all our money on health and benefits
Before this popular US narrative takes off on this thread, can I point out that those of us actually in the UK remember that at the same time the (then Tory) UK govt was slashing the army, it was also slashing disability spending and boasting it was going to cut billions of pounds from the welfare state.
The Tories explicitly ran on this in an election – IIRC 2015 though can't be bothered to check.
It's just that the third thing the UK govt was cutting was taxes. The Tories ran on that as well.
Obviously it works better for the US elite like Trump, but by no means limited to him, to kid US citizens that there's a straight choice between them having affordable healthcare etc and them having a good military, while gliding over taxcuts which disproportionately benefit the wealthy, but that's just a version of the game "He took your cookie".
In fact I saw a US poster respond to a recent budget by this Labour government which announced signficant cuts to disability spending, with words to the effect of "See, spending on welfare not military." The opposite of what had happened. So it's a very deeply entrenched view.
(As it happened a Labour revolt subsequently reduced the intended cuts, IIUC, but the US poster's comment came before that happened.)