Journalists were not invited, although photos provided by Ms. Haley’s office showed mangled hunks of metal, the drone and other items that were part of the presentation she made in December. The provenance of the displayed pieces, including when and where they were collected, was not explained.
“We wanted to bring the Security Council members to see the material so they could decide for themselves,” Ms. Haley said in a statement. “We believe what the council saw today makes it clear that the evidence continues to grow that Iran is blatantly ignoring its international obligations.”
Iran’s foreign minister, Mohammad Javad Zarif, wrote on Twitter that the field trip had been an attempt “to create an Iranphobic narrative at the UN Security Council through wining and dining and fake ‘evidence.’”
Neither Ms. Haley nor Mr. Trump articulated what the administration had hoped to achieve from the visit. Iran is already subject to United Nations sanctions limiting arms sales. Russia and China, which have veto power in the Security Council, are unlikely to support additional restrictions.
In televised remarks at the start of the lunch, Mr. Trump said only that the ambassadors had viewed “a display of Iranian missiles and arms that the regime has transferred to its militant allies in Yemen.”
The ambassadors later visited the United States Holocaust Memorial Museum in Washington to see an exhibit about atrocities in Syria’s war, another issue that has bitterly divided the Security Council.
“There’s a real imperative to focus the Security Council and indeed member states around the world on the bad stuff Iran is doing,” said David Pressman, a former United Nations ambassador under the Obama administration who is now a partner with the law firm Boies Schiller Flexner. “The concern that I have is that it doesn’t appear to be part of a larger strategy calculated to lead to much more than a powerful photo opportunity.”
Most of the ambassadors from the other 14 Security Council members refrained from commenting publicly about the day of touring.
On Twitter, Ambassador Jonathan Allen of Britain said that the representatives had been shown “clear evidence” that Iranian-made weapons were used by Houthis in Yemen, though it was unclear whether he believed Iran’s government was guilty of sanctions violations.
He posted photographs of welding on a missile that he said indicated the weapon had been “cut in half, presumably for smuggling.” He wrote that the date stamp suggested the weapon had been delivered after the arms embargo on Yemen had taken effect.
Most of the materials were provided to the United States government by Saudi Arabia, Iran’s main regional rival. Saudi Arabia and Iran have been locked in what is essentially a proxy war in Yemen, and human rights groups say both sides are guilty of abetting a colossal humanitarian disaster.
Saudi Arabia, which has backed the Yemeni government, leads a military coalition that has conducted a campaign of punishing airstrikes on Yemen since March of 2015.
This month, a United Nations panel concluded in a confidential report that Iran had violated the arms embargo imposed on Yemen by failing to prevent Houthi rebels from obtaining Iranian-made missiles, including a missile that crashed near an airport outside the Saudi capital of Riyadh in November.
But the report stopped short of accusing Iran of actually supplying the weapons.