DUBAI, United Arab Emirates (AP) — The U.S. Navy seized a large cache of weapons being smuggled by two small ships off the coast of Somalia, it announced Tuesday, amid the grinding war in nearby Yemen.

Among the arms seized by guided-missile destroyer USS Winston S. Churchill in the Indian Ocean last week were thousands of Kalashnikov-style rifles, light machine guns, heavy sniper rifles, rocket-propelled grenade launchers and crew-served weapons, the Navy said.

In its statement, the Navy’s Bahrain-based 5th Fleet did not identify the source of the smuggled weapons or reveal their destination. But a U.S. defense official who spoke on condition of anonymity, as he wasn’t authorized to discuss details of the seizure, said there were “some indications” the arms were bound for war-torn Yemen just across the Gulf of Aden. Authorities were continuing to investigate, the official added.

Over the course of two days, the destroyer halted and searched the two ships for illicit cargo as part of the Navy’s routine maritime security patrol in the region. Those aboard the vessels were released after the operation, it added.

A short video released by the Navy appeared to show U.S. sailors inspecting one of the intercepted dhows, a traditional ship that commonly sails the waters of the Persian Gulf region, as helicopters circled overhead. Photographs of the contraband, a sample of the much larger quantity of arms, showed rows of what appeared to be new Kalashnikovs wrapped in plastic and piles of rocket-propelled grenade launchers.

“These operations prevent nefarious actors from illegally spreading their lethal aid,” said Cmdr. Timothy Shanley, commanding officer of the Churchill.

The assortment of arms aboard the dhows mirrored other shipments interdicted by the U.S. and allied forces in the region that later were found to be heading to Yemen, where Iranian-backed Houthi rebels have been battling a Saudi-led military coalition for control of the country since 2015. Yemen is awash with small arms that have been smuggled into poorly controlled ports over years of conflict.

Analysts say the pattern of the shipment matched past instances of suspected Iranian smuggling into Yemen. Last June, for example, Saudi naval forces seized a dhow carrying anti-tank missiles and thousands of assault rifles believed to have been manufactured in Iran. They were on their way to Yemen via smuggling networks in Somalia, according to a recent report by the Global Initiative Against Transnational Organized Crime.

“The unique blend of material is consistent with multiple interdictions over the years that have been definitively linked back to Iran,” said Tim Michetti, an expert on illicit weapons flows, of the seizure revealed Tuesday.

“Co-mingled with items identical to those recovered from Iran-aligned groups in the region,” he added, the assortment “provides a strong indication of a transfer’s provenance.”

Arab countries, the West and United Nations experts allege that Iran has armed the Houthis with everything from assault rifles to ballistic missiles, something long denied by Tehran despite evidence to the contrary. The 5th Fleet repeatedly has accused Iran of smuggling arms via the Arabian Sea to the Houthis, which hold Yemen’s capital, Sanaa, and much of the country’s north.

Iran’s mission to the United Nations did not immediately respond to a request for comment on the interception.

The interdiction comes at a delicate time in Yemen and the wider region. Houthi forces have pushed aggressively into Yemen’s last remaining government stronghold of Marib in recent weeks. Tensions are rising between Iran and the United States over the tattered 2015 atomic deal that sought to limit Iran’s uranium enrichment in exchange for sanctions relief.