The negotiations were interrupted by an escalation of the Seminole War, and in December 1818, Monroe ordered General Andrew Jackson to enter Florida and retaliate against Seminoles that had raided Georgia. Exceeding his orders, Jackson captured the Spanish outposts of St. Marks and Pensacola and executed two Englishmen. While Jackson's actions outraged the rest of the cabinet, Adams defended them as necessary to the country's self-defense, and he eventually convinced Monroe and most of the cabinet to support Jackson.[75] Adams informed Spain that its failure to police its own territory had compelled Jackson to act, and he advised Spain to either secure the region or sell it to the United States.[76] The British, meanwhile, declined to risk their recent rapprochement with the United States, and did not make a major diplomatic issue out of Jackson's execution of two British nationals.[77]
Negotiations between Spain and the United States continued, and Spain agreed to cede Florida. The determination of the western boundary of the United States proved more difficult. 