Houthi rebels claim they shot down a US drone over Yemen’s Dhamar governorate, south-east of Sanaa.
On Wednesday, the US military’s Central Command said it was investigating the reports.
The Iran-backed rebel group is believed to have used a surface-to-air missile to hit the US MQ-9 Reaper drone, made by California's General Atomics, late on Tuesday, US military officials told Reuters.
“It appears to have been fired by the Houthis and enabled by Iran,” the official said.
On Wednesday, Yahia Sarie, a military spokesman for the Houthis, said in a statement their air defences downed a US MQ-9 drone on Tuesday over the northern city of Dhamar.
"The rocket which hit it was developed locally and will be revealed soon at a press conference," he said.
The US military's Central Command said in a statement that it was investigating the Houthi claims that they attacked an unmanned US drone "operating in authorised airspace" over Yemen.
"We have been clear that Iran's provocative actions and support to militants and proxies, like the Iranian-backed Houthis, poses a serious threat to stability in the region and our partners," said US Army Lt. Col. Earl Brown, a Central Command spokesman.
It is the second time the rebels have destroyed a US drone in Yemen. In June, the US military said the
Houthis had shot down an American drone with assistance from Iran.
The MQ-9 is one of the main attack and surveillance drones operated by the US and has been in service since the mid-2000s, a period during which the US ran a significant drone campaign in Yemen against Al Qaeda in the Arabian Peninsula.
While the US military claimed significant numbers of terrorists were killed, human rights groups criticised the programme for its high number of civilian casualties. Experts questioned the effectiveness of the programme as a way to counter the terrorist threat.
In the chaos at the start of the war in Yemen, Aqap seized ground and staged attacks, while in the ongoing fighting and general lawlessness in many areas, ISIS has also emerged as a disruptive factor.
The downing of the MQ-9 drone comes as tensions between Iran and the US have risen since President Donald Trump’s administration last year abandonded an international deal to curb Tehran’s nuclear ambitions and began to ratchet up sanctions.
On June 20, Iran’s Islamic Revolutionary Guard Corps shot down a US RQ-4A Global Hawk surveillance drone over the Strait of Hormuz. The US responded with cyber attacks on IRGC missile-control systems and announced new sanctions on several Iranian officials.
After the incident, Mr Trump ordered retaliatory strikes on Iranian missile systems and radar sites, but these were called off 10 minutes before launch.
Mr Trump said this was because he learnt that the casualty estimate was 150, a number he said was not proportionate to the downing of a drone.
Iranian Foreign Minister Javad Zarif said yesterday that Tehran may act unpredictably in response to what he called Washington’s unpredictable policies under Mr Trump.