ABOARD THE USS JASON DUNHAM, PERSIAN GULF — U.N. experts on Thursday inspected a shipment of weapons recently seized by the U.S. Navy that American officials suspect could provide new evidence of Iranian support for Houthi rebels in Yemen.

The U.N. inspectors will seek to identify the origin of about 2,500 AK-47s seized in the Gulf of Aden on Aug. 28, U.S. officials said.

The weapons are being stored aboard the USS Jason Dunham, a guided-missile destroyer that confiscated the weapons from a vessel encountered about 70 miles off the southern coast of Yemen.

Vice Adm. Scott Stearney, the commander of U.S. naval forces in the Middle East, said American officials had conducted a preliminary examination of the weapons but would wait to determine how to handle them until the U.N. investigators reach their own conclusions.

“What the U.N. inspection team does is it allows us to have a level of validation that maybe is accepted on a broader scale,” Stearney told a small group of reporters. The team members have expertise in weapons coming out of Iran, Yemen and Somalia, “so, everything that connects this portion of the theater,” he said.

The seizure comes as the Trump administration seeks to choke off outside support to the Houthis, who have been battling Saudi Arabia, a U.S. ally, and other nations since 2015. The United States provides limited military support to the Saudi-led military coalition, which conducts air and ground operations in Yemen, including aerial refueling and intelligence support.

Critics allege that American support has enabled the Saudi-led coalition to conduct an air campaign resulting in repeated targeting of civilian sites and widespread noncombatant casualties, even as the war exacerbates a humanitarian crisis. U.N. officials this week declared that half of Yemen’s population now lives under “pre-famine conditions.”

At least 21 Yemeni civilians were killed Wednesday in airstrikes on a market in the Red Sea port of Hodeida, according to the U.N. humanitarian aid ­agency.

Friction over Riyadh’s handling of the war had been growing even before relations with the United States plunged into crisis over the death of Washington Post contributing columnist Jamal Khashoggi, who Saudi officials have admitted was killed in the country’s consulate in Istanbul this month.

Since the war in Yemen began, U.S. and allied naval forces have seized weapons shipments that the U.S. government believes originated in Iran and were bound for the Houthis, a Shiite group that took over the capital almost four years ago.

Cmdr. John Hamilton said the ship’s helicopter had taken video of two small boats, a skiff and a traditional dhow, transferring cargo at sea at night. The following morning, the Dunham dispatched personnel, who determined that the vessels were not flagged and thus considered stateless. After boarding the skiff, the U.S. team recovered weapons wrapped in plastic and Styrofoam casings.

Three crew members from the skiff boarded the Dunham after U.S. officials determined that the craft, which had been weighed down with the guns, was no longer seaworthy. The men were handed over to Yemeni authorities, officials said, and the skiff was destroyed. Officials were unable to recover 500 AK-47s from that vessel.

Naval officials provided reporters access to the weapons, which were stacked about five feet high and four weapons deep on the Dunham. The guns, which officials said were new when they were confiscated, are quickly rusting in the sea air.

U.S. officials believe the interdicted vessels embarked from Somalia and suspect the shipment may have been made with Iranian support.

Gregory Johnsen, who previously served as a member of the United Nations’s Yemen Panel of Experts, said the inspectors in addition to examining the weapons probably would ask for documents that were found on the boat, information about communications its crew might have had with shore, and might also ask for information including maps to determine the vessel’s trajectory. Establishing origin will be more difficult since they are small, commonly available arms rather than larger ­weaponry.

Determining that the weapons are linked to Iran would reinforce the Trump administration’s assertion that the country is providing lethal aid to the Houthis.

In recent months, the White House and State Department have injected new urgency in their push against Iran’s military reach and intensified economic measures on Iranian affiliates.

The Trump administration has displayed other seized arms allegedly linked to Iran at a military base outside Washington. U.S. officials have also accused Iran of supplying more sophisticated weapons to the Houthis, including ballistic missiles that threaten Saudi Arabia.

Securing commerce around Yemen, which sits along some of the most heavily transited waters in the world, has become a priority for the Pentagon because of the Houthis’ military power and their record of attacking vessels linked to Saudi Arabia or its supporters. The Bab al-Mandeb, where the southwest tip of Yemen is only 18 nautical miles from the Horn of Africa, is a particular concern because of the volume of oil and commercial goods that transit it.

“So, trying to thread that needle while it’s moving is something we’re really good at in the military, but we have to be good at it in a very, very collective way,” which includes working with an international naval coalition that battles piracy and terrorism, Stearney said.

Sudarsan Raghavan in Cairo contributed to this report.