If you are a citizen of the USA, you can just book a plane before the draft. Down South you don’t have to get visas most of the time and you can then just overstay your inexistent visa. Might be some trouble and cost adapting but it’s better than dying in Ukraine and I don’t think it’d be that much cheaper to go to Mejico that the alternative becomes prohibitive. You can even do the ol’ “Actually I just enrolled into university so I can’t fight” trick since Argentina and a few others have plenty of open admission zero-tuition universities.