Even after the Defense Secretary and the National Security Advisor explained why that would be a very bad idea, Trump persisted, noting how the invasions of Grenada and Panama were successful. Of course, the historically and geographically ignorant Trump doesn't remember that neither invasion was about taking over a country.
Only a small part of the tiny island country of Grenada was occupied by American forces to evacuate some students. And in Panama, the American military was in country to extradite its dictator Manuel Noriega and only occupied portions of the capital to help secure an orderly transition of government.
Nonetheless, even after Trump's staff talked the idea down, he later brought it up in discussions with the president of Columbia. And then, yet again in talks with four Latin American leaders, he brought it up once more, and each of the four told him it was a bad idea.
Nonetheless, Trump still persisted. Once again, the National Security Advisor had to explain why it was a really bad idea.
As the linked article notes, this "underscores how [Trump's] 'America First' foreign policy at times can seem outright reckless, providing ammunition to America’s adversaries." Not to mention that it makes him, once again, look like a gigantic hypocrite, given he insisted his administration would never be involved in foreign adventures while he labeled Hillary Clinton as "trigger happy" (source here).
Once again, Trump has embarrassed America abroad and given this country the reputation of being dangerous. It's incredible how much damage he's done diplomatically in a year and a half.