Brazil
The second highest numbering force in the American continent after the United States is that of the Federative Republic of Brazil, which is deemed very powerful. With a navy, air force, and an army, combined, the military employs about 335K active and a whopping 1.34 million reserved personnel waiting for a call to action.
The sixth Brazilian Republic (established in 1985) has, however, not fought many wars. And, of course, messing around with a coastal nation with such an impressive force might get a bit expensive. They came out victorious in the Angolan Civil War of 1975, as well as Operation Traira in 1991.