Who is always a party in federal cases

In Federal criminal cases, the United States government is always a party. In essence, the Federal government brings the case as a representative of the people against the person who broke the law.

In Federal civil cases, the parties can change and this question does not apply. This question should instead say "Who is always a party in federal criminal cases?"

they thoght they were going to nuke each other

to force terrorists groups to stop attacking western targets using massive military force.