But speaking at the Farnborough International Airshow in Hampshire on Monday, the Prime Minister failed to guarantee the project’s future.
“It is an important programme and I know that people in the room will want to hear me say that,” he said when asked if its future was “on the table” during the review.
“It is a programme on which we are making significant progress in my view and the Defence Secretary is holding a ministerial-level meeting I think next week in relation to this because of the significant benefits here in this country.
“That is my attitude to it. There is of course a review going on but it is important for me to put on record just how important a programme this is.”
‘Essential for the future’
Jonathan Reynolds, the Business Secretary, later appeared to offer more concrete reassurances on the project’s future, insisting that the Government was “strongly committed” to the scheme.
“We see it as essential for the future, not just in terms of our defence needs but, obviously, our industrial needs,” he said.
The multi-billion pound Global Combat Air Programme, as Tempest is officially known, employs 3,500 people in Britain, a workforce that had been expected to double in the coming years.
But there are worries within the defence industry that the programme could be scaled back as Labour reviews the state of the Armed Forces.
Leaders in Japan and Italy have pressed Sir Keir and his ministers about the project.
BAe Systems, the company building the jets with the help of other firms, has also issued a statement stressing that the programme provided “critical sovereign combat air capability”.
Sir Keir has not matched the Conservative pledge to spend 2.5 per cent of GDP on defence by 2030, instead saying the target would be reached at an unspecified date in the future.
Labour’s strategic defence review is due to be published in the first half of 2025.