FILE - Photographers take pictures of what officials described as an Iranian Qasef drone captured on the battlefield in Yemen during a news conference in Abu Dhabi, United Arab Emirates, June 19, 2018.
FILE - Photographers take pictures of what officials described as an Iranian Qasef drone captured on the battlefield in Yemen during a news conference in Abu Dhabi, United Arab Emirates, June 19, 2018.

DUBAI, UNITED ARAB EMIRATES - In Yemen, the high-pitched whine of drones has been a part of life for over 15 years, ever since the first U.S. drone strike targeting al-Qaida in 2002. On Thursday, an attack on a military base where America once ran its drone program showed that the U.S. is no longer the only force deploying them.

The attack by Yemen's Shiite Houthi rebels that killed at least six people shows how the Arab world's poorest country has become one of the world's top battlefields for drones. Both the rebels and the Saudi-led coalition fighting them, as well as the U.S., continue to use them for surveillance and attacks.

But while the U.S. uses American-made drones and the coalition has turned to Chinese suppliers, the manufacturer of the Houthis' drones in both the air and the sea has been a contentious question.

FILE - The remains of an Iranian Qasef-1 Unmanned
FILE - The remains of an Iranian Qasef-1 Unmanned Aerial Vehicle, a warhead-carrying weapon used to dive on targets, are shown during a press briefing at Joint Base Anacostia-Bolling, Dec. 14, 2017, in Washington. This drone was fired by Yemen into Saudi

?The Iran link

A 2018 report by a U.N. panel of experts on Yemen looked particularly at the Houthis' Qasef-1 drone.

"Although Houthi-aligned media announced that the Sanaa-based Ministry of Defense manufactured the [drone], in reality they are assembled from components supplied by an outside source and shipped into Yemen,'' the report said. The Qasef, or Striker, "is virtually identical in design, dimensions and capability to that of the Ababil-T, manufactured by the Iran Aircraft Manufacturing Industries.''

The Ababil-T can deliver up to a 45-kilogram (100-pound) warhead up to 150 kilometers (95 miles) away.

The Qasef-2K, which the Houthis said they used in Thursday's attack, similarly resembles the Iranian designs.

A research group called Conflict Armament Research, with the permission of the United Arab Emirates' elite Presidential Guard, also examined seized drones used by the Houthis and their allies to crash into Patriot missile batteries in Saudi Arabia. 

The research group similarly said those drones shared "near-identical design and construction characteristics'' of Iranian drones.

FILE - A craft described as a "drone boat," once l
FILE - A craft described as a "drone boat," once loaded with explosives by Shiite rebels in Yemen, is displayed at a military installation in the United Arab Emirates, June 19, 2018. Officials involved in the Saudi-led campaign against Shiite rebels in Yemen, known as Houthis, showed journalists materiel captured on the battlefield that they alleged show Iran's hand in arming the rebels.

?The drone boat

Coalition forces last year also showed journalists a Houthi "drone boat'' filled with explosives that failed to detonate.

The officials also shared black-and-white images they said had come from the "drone boat.'' They said the pictures and associated data from the boat's computer showed Iranians building components for its guidance system in eastern Tehran, with a hat in the background of one picture bearing the symbol of Iran's hard-line paramilitary Revolutionary Guard.

They said those involved in building the components probably believed it would be destroyed in the blast, so they didn't wipe the computer's hard drive.

For its part, Iran repeatedly has denied supplying the Houthis with drone or ballistic missile technology. However, Iran would have an interest in seeing Saudi Arabia, its archrival in the region, tied down in a bloody, protracted conflict with no clear end in sight.