system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5:How does "declaring war" on a country work? And how does a country know who is attacking them? Couldn't the US go bomb a country and say another country did it?
gpt
Yes, a country's leader could go attack another country and blame someone else. However, the complexities in chain of command and the number of people that would be required to know are so high that people would find out eventually. Even Russia, which Putin keeps on lockdown with state-controlled news and the like, couldn't keep their invasion of Ukraine a secret indefinitely. With a free press and a division of power like in the US, it wouldn't take long at all for someone to start putting the pieces together.

At the very least, if the President did start to wage some sort of "secret war" without Congressional consent, eventually things like soldiers and ammunition and fuel would start going absent. When it came time for Congress to pay the bills, they'd find out and be pretty upset because it's exclusively their power to be able to formally declare war.

World War 1 was officially declared by the German diplomat to the Russian prince, to give an example. Nowadays it's difficult to say how a country like the US would declare war against an equivalent power, because would you really want to give a nuclear power forewarning that you're about to attack?