Britain may not order 138 stealth F-35 warplanes as originally pledged, as the Defence Secretary has suggested that the final number will depend on the results of a national security review.
The UK is currently embarked on a £9.1 billion programme by 2025 to purchase 48 of the F-35s.
The jets are reportedly the world’s most advanced, made American aviation giant Lockheed Martin.
Britain currently has 13 of the jets in the United States being tested ahead of flight trials off HMS Queen Elizabeth next year - but has pledged to purchase 138.
Gavin Williamson was speaking at the commissioning of the UK's biggest and most powerful warship, HMS Queen Elizabeth - which will see the jets conduct missions from its flight deck.
When pressed by ITV News on whether Britain will receive all 138 following suggestions it might be a smaller number, he said:
"What we are going to be doing is making sure that HMS Queen Elizabeth has the jets that she needs as well as HMS Prince of Wales.
"We are doing a national security and capability review and looking at what we need, and we will choose the number we need in order to be able to operate.
"The F-35s are not just about supporting the carriers, it's actually about supporting the work that the RAF do, and the Navy do, and the Army do, in all parts of the world."
But Permanent Secretary, Stephen Lovegrove, when addressing the same suggestion at a Public Accounts Committee this week, dismissed it.
He told MPs:
"I see no reason at the moment, and I have had no indication from either political sources or indeed from our financial sources within the department, that the ambition to get 138 has been at all moved away from.
"Of course it is always possible that someone may change their mind. But I have seen no indication whatsoever of that happening."