Upvote:5
To name just a few of the better-known instances:
Notes:
Upvote:18
Yes, the USA has frankly engaged in unilateral military action so many times, it would be serious work just to count them all.
Just among declared wars, three of the five (a bare majority) were one-on-one wars that the USA declared first.
Among non-declared wars, this has been a common scenario. Presidents Reagan and Bush in the 1980s engaged in 3 of them that I can think of off the top of my head (Grenada, Panama, and the Libyan bombing).
Interestingly the official Marine hymn mentions two such military actions in the first line: The Mexican/American War, and the First Barbary War.