WASHINGTON — A Navy warship has seized a "significant cache" of suspected Iranian guided missile parts headed to rebels in Yemen, U.S. officials said Wednesday, marking the first time that such sophisticated components have been taken en route to the war there.

The seizure from a small boat by a U.S. Coast Guard boarding team from the U.S. warship happened last Wednesday in the Arabian Sea, and the cache, which included weapons and advanced missile components, has been linked to Iran, officials said.

The incident illustrates the continuing illegal smuggling of weapons to Houthi rebels, they said, and comes as Secretary of State Mike Pompeo and Israeli Prime Minister Benjamin Netanyahu were meeting, with Iran as the main topic.

The officials spoke on condition of anonymity to describe a sensitive military mission.

The U.S. has consistently accused Iran of illegally smuggling arms to Houthi rebels battling the Yemeni government and has seized smaller and less sophisticated weapons in transit. The officials described the missile parts found in this latest incident as more advanced than any others previously seized.

The guided-missile destroyer USS Forrest Sherman MC2 William Jamieson / U.S. Navy file

The USS Forrest Sherman was conducting routine maritime operations when sailors noticed a small boat exhibiting behavior similar to other vessels involved in smuggling, a Defense official told NBC News. By the time the U.S. Navy warship approached, the vessel was "dead in the water" due to engine failure. The boat was not flying a flag, and the Navy and Coast Guard personnel boarded it for inspection and flag verification — a process allowed under international law. Once onboard, they found the weapons.

The crew of the boat were Yemeni, the official said, and the military is still investigating the origin and exact destination of the boat.

Officials did not provide the exact number of weapons seized last Wednesday, but did describe it as a significant cache, and one official said early assessments indicate it was headed to Yemen. The officials said the small boat was towed into port because a leak was discovered during the inspection, and the crew were transferred to custody of the Yemeni Coast Guard. The weapons are still on board the U.S. ship.

The officials said the U.S. is still examining the weapons to specifically pinpoint their origin. But they said the missile parts had all the hallmarks of previous Iranian weapons that have been found in Yemen or Saudi Arabia.

Smuggling weapons into Yemen is a violation of a U.N. Security Council resolution.

The Iranian government did not immediately respond to a request for comment, but it has long denied supplying arms, including missile parts, to the Houthis.

Houthi rebels control much of northern Yemen, and a Saudi-led coalition, allied with the internationally recognized government, has been fighting them since 2015. A localized cease-fire in the port of Hodeida was brokered last December by the United Nations but was never fully implemented. Saudi Arabia has been holding indirect talks with the Houthis in Oman, and officials have said that momentum is building in other efforts to end the war.

On at least six occasions between 2015 and 2019, the U.S. and its allies have seized suspected Iranian weapons during similar ship inspections. In those cases, however, the arms were smaller and less sophisticated.

Nearly two years ago, U.S. officials laid out a display of truck-sized missile remnants at a military base in Maryland, telling reporters that they had been launched into Saudi Arabia from inside Yemen. At the time, then-U.N. Ambassador Nikki Haley said U.S. intelligence experts had concluded "unequivocally" that the weapons came from Iran.

Seized assault weapons are piled into a corner below the deck of the guided-missile destroyer USS Jason Dunham on Oct. 24, 2018 after they were seized from a small boat en route to Yemen. Lolita Baldor / AP

Haley and the Trump administration used the display to substantiate repeated claims that Iran had been funneling weapons to Houthi rebels in Yemen.

While the U.S. did not point to a specific delivery of the weapons remnants by Iran to the Houthis, officials said that markings and other characteristics indicated the missiles were manufactured in Iran. One shredded piece of metal displayed to reporters bore the logo of Shahid Bakeri Industrial Group, an Iranian defense entity under U.S. sanctions. And others had specific technical characteristics, such as a certain valve, that only Iranian missiles have.

At the time, the Iranian government insisted that it was not sending missiles to Yemen, where Shiite Houthi rebels aligned with Iran have taken over much of the country. Iran's envoy to the U.N., Gholamali Khoshroo, called the accusations "fake and fabricated" evidence that illustrates America's "irresponsible, destructive and provocative role" in the region, according to a statement.