NewYork times--  The ambassadors were also White House lunch guests of President Trump, who pressed them to counter “Iran’s destabilization activities in the Middle East.”

The missile fragments, along with other military equipment, were first claimed last month by Nikki R. Haley, the American ambassador to the United Nations. She presented them as claim that Iran had violated United Nations sanctions on supplies of weaponry to Houthi group in Yemen, where more than 10,000 people have died in a war that began three years ago by Saudi Arabia.

At the time, weapons experts said the presentation — of fragments of what military officials said were Iranian-made Qiam missiles, as well as a drone and an antitank missile — had failed to prove conclusively that Iran violated any sanctions.

It was unclear on Monday whether Ms. Haley, who led her Security Council colleagues on the tour at Joint Base Anacostia-Bolling, provided additional material to bolster the administration’s case.