Iran retaliated Monday for the U.S. attacks on its nuclear sites by targeting Al Udeid Air Base, a sprawling desert facility in Qatar that serves as a main regional military hub for American forces. President Donald Trump said in a social media post that no Americans were harmed and “hardly any damage was done.

Iran coordinated its strikes on U.S. bases in Qatar, prompting air space closure, a source familiar with the matter told Reuters on Monday. The New York Times, which first reported the coordination, said Iran took the action to minimize casualties.