The funding request came as a US F-35 fighter jet had to make an emergency landing at a US air base on Thursday “after flying a combat mission over Iran”, a spokesperson for the US Central Command said.

The jet landed safely and the pilot is in stable condition, the spokesperson said. The F-35 was struck by suspected Iranian fire, US media reported, citing unnamed sources.

The Pentagon estimates each such jet costs up to $77m.

“This incident is under investigation,” the Central Command spokesperson said.

At a news conference on Thursday, Hegseth said the defence department needs more money for “what we may have to do in the future”.

The $200bn request is in addition to the department’s annual budget of $838.7bn, which was approved by Congress in January.

Congress has separately approved $188bn in funding for aid to Ukraine since the Russian invasion in February 2022. About $110bn had been spent as of last December, according to the special inspector general tracking the funding.

Republican House Speaker Mike Johnson said on Thursday that he was sure the $200bn request for the Iran war was “not a random number”.

“Obviously it’s a dangerous time in the world, and we have to adequately fund defence, and we have a commitment to do that,” he said.

The US-Israel war with Iran has had other economic impacts in the US. The associated spike in oil prices has raised economic uncertainty and threatened to drive up inflation.

The US central bank, though, voted this week to hold interest rates steady. Raising them could have been an indication that bankers are worried about inflation and wanted to increase borrowing costs to stem spending and hence slow down price rises.

The administration’s war-funding request will set up a bruising legislative fight with Congress – which must approve funding – less than eight months from November’s midterm congressional elections.

While military funding tends to garner bipartisan support, polls suggest a majority of the US public does not approve of the war in Iran – and politicians will be pressed to justify the massive spending increase being requested.

Some lawmakers suggested that Trump’s decision to begin strikes without consulting Congress may make it difficult to win support to fund the attack now.

Democratic congressman Jim Himes said Hegseth should “remember that old saying”.

“If you want me there for the landing, make sure I’m there at the takeoff.”