President Trump said Saturday "we've knocked out 42 navy ships" in three days, adding that the US is doing "very well" in Iran.Why it matters: Trump bragged about dominance in Iran and hinted at possible action in Cuba at the first Shield of the Americas Summit, which has outgoing Homeland Security Secretary Kristi Noem at the helm.The summit underscores Trump's willingness to reassert American control under his so-called "Donroe Doctrine," though modern U.S. presidents have typically shied away from exerting as much American influence over the Western Hemisphere."We knocked out their Air Force. We knocked out their communications, and all telecommunications has gone," Trump said of Iran. The other side: Iranian foreign minister Seyed Abbas Araghchi said on X Saturday the Iranian president "expressed openness to de-escalation within our region-provided that our neighbors' airspace, territory, and waters are not used to attack the Iranian People.""Gesture to our neighbors was almost immediately killed by President Trump."State of play: The U.S. president said the focus right now is on Iran but he'll "take care" of Cuba.The Trump administration had already indicated an openness to regime change in the country and is investigating the Cuban government's claim it killed four people aboard a Florida-tagged boat near the Villa Clara coast last month."Cuba's at the end of the line," Trump said. "They're very much at the end of the line. They have no money. They have no oil. They have a bad philosophy. They have a bad regime that's been bad for a long time."Context: The summit comes as the president devotes much of his second term reshaping global trade while strong-arming southern leaders to commit more resources to stopping illegal immigration."After years of neglect, President Trump established the 'Donroe Doctrine' to restore American preeminence in the Western Hemisphere," White House spokesperson Anna Kelly told Axios in an emailed statement."The President has successfully strengthened our relationships in our own backyard to make the entire region safer and more stable."Here's what to know about the summit:Who's attending?Secretary of State Marco Rubio, Defense Secretary Pete Hegseth, Commerce Secretary Howard Lutnick and United States Trade Representative Jamieson Greer join Trump in Doral, Florida on Saturday.Noem also attended in her new role as special envoy to the Shield of the Americas.The coalition is stacked with America's "strongest likeminded allies" in the hemisphere, a brief State Department news release notes.They include, per a White House official:Argentine Republic President Javier MileiBolivian President Rodrigo Paz PereiraChile President-elect José Antonio KastCosta Rican President Rodrigo Chaves RoblesDominican Republic President Luis AbinaderEcuadorian Constitutional President Daniel NoboaEl Salvadoran President Nayib BukeleGuyanese President Mohamed Irfaan AliHonduran President Nasry "Tito" AsfuraPanamanian President José Raúl Mulino QuinteroParaguayan President Santiago PeñaTrinidad and Tobago's Prime Minister Kamla Persad-BissessarThe intrigue: Trump-installed Venezuelan President Delcy Rodríguez — who came to power after Trump captured former leader Nicolás Maduro, in one of Trump's most high-profile examples of executing the "Donroe Doctrine" — will not attend.What's the summit's goal?A White House spokesperson told Axios that the initiative will "advance cutting-edge strategies to defeat narco-terrorist cartels and stop illegal mass migration to make America and the entire Western Hemisphere safer."The president is also expected to tout a newly-signed joint security declaration that reaffirms the U.S. and 17 leaders across the hemisphere's "commitment to peace, sovereignty and stability in the region."Go deeper: How the ice finally broke under Kristi NoemEditor's note: This story has been updated with remarks from President Trump and the Iranian foreign minister.