The US defense complex is large but it’s also inefficient and sclerotic, partly as a direct result of those fat budgets that have created a many decades old culture of graft and waste.

A country with less of this cost disease could probably be competitive with 1/4 the spend or less, especially if they skip big heavy Cold War era tech in favor of faster cheaper stuff like drones and smart munitions. Aircraft carriers and manned fighters look cool but I’m not sure how much they matter anymore.

What I see from the EU is that while they do also have cost disease, it might not be as entrenched in that sector. They also have Russia directly adjacent to them, which motivates people to actually care.

If Mexico were belligerent with a history of imperialism, had nuclear weapons and a huge army, and had just invaded and taken Cuba, we’d be in a similar situation and similarly motivated. As it stands we have a “big beautiful ocean” between us and Russia and do not face a direct threat. The US is almost uninvadeable unless you sterilized it with nukes first, and we have those too.