Iran might be advancing its support for the Houthi movement in Yemen, according to a senior US State Department official.

“I think Iran’s support to Houthis, especially in areas like sending advanced weapons, is continuing without any diminution,” the official said on Tuesday.

“They might even be stepping it up.”

Iran’s support, it was claimed, enables the Houthi-led forces to “threaten” Saudi Arabia by launching advanced missiles at civilian airports and “potentially” threaten US citizens.

The official also mirrored the position of aid agency, USAID who earlier in the week warned it will suspend its humanitarian aid programme in “Houthi-controlled areas” in Yemen if the movement fails to remove impediments obstructing aid operations. The official went on to say that the US hopes that Houthis will “change their behavior” and the measures to limit aid will not be necessary.

Yemen is facing the world’s worst humanitarian crisis as a result of the US-backed, Saudi-led coalition’s military intervention in the country since 2015, seeking to overthrow the Houthi-aligned government which controls much of the north including the capital Sanaa. The Yemen Press Agency reported that coalition warplanes had conducted 25 air strikes over Yemeni provinces in the past 24 hours.

Last week a paper reported that the Houthis are developing locally manufactured drones which are increasingly becoming deadlier and more accurate, the paper found that some components in retrieved drones include those found in recovered Iranian downed drones in Iraq and Afghanistan. In December of last year, Iran and the Houthi-led National Salvation Government signed a military cooperation agreement, representing the first formal deal between the two parties.