President Trump chaired a meeting of the UN Security Council on Wednesday, leading a more or less restrained discussion of non-proliferation issues. He delivered prepared remarks focused on touting his diplomatic outreach to North Korea and expanding the case against Iran that he had made in his General Assembly remarks. The 14 other members then spoke, with even Kuwait arguing in favor of the Iran deal.
Why it matters: Historically, such a forum allows a U.S. president to put a difficult issue on the international agenda and push other countries toward progress, however uncomfortable the decisions involved. The meeting Trump led did little to advance solutions to national security challenges, other than underscore U.S. isolation on Iran (despite valiant efforts from President Macron of France to highlight areas of agreement).