Few would consider it unethical to fund wars of self-defense. But self-defense is not a clear term, see for example the Bush Doctrine and preemptive war. America has a historical habit of funding its future enemies, and in more current wars of simply maintaining the status quo.
One of the more unfortunate political outcomes I've noticed from the Bush era is a tendency for people to take the tragedies of US foreign policy in the Middle East and project them onto every conflict involving the US since then (this is not targeted at you).
So you end up with well-intentioned individuals who strive for peace and opposed the Iraq War (or eg Vietnam), who find themselves siding with the autocracy invading its sovereign neighbors, for the simple fact that it positions itself as a force against American hegemony and must therefore inherently be "the good guys".
Either way, I sympathize with your point more generally, and also wouldn't like to see my tax dollars spent on drone striking weddings.
You have an interesting point of view and given me food for thought, thank you.
Wrt to the present, I think the current (US) military actions are simply a means of moving wealth from one segment of the population to another without a need for transparency. Hence, less tax dollars should go in.
I'd prefer to regress to the time when our government needed to fund war by asking people to purchase liberty bonds.