A British investment of £2 billion in the US-built joint strike fighter - is being put at risk owing to American reluctance to share key technology which will make it operable.
First flagged up by the Blog last June, British defence officials are increasingly worried by the difficulty in getting access to the vital "source codes" which control the software which enable the complex JSF to operate.
With the aircraft now set to move into the production phase, with the UK having committed over £2 billion to its development and production, dealings with the US over this issue are getting "thornier".
Lord Bach, Britain's defence procurement minister, stresses that the UK is "looking forward" to the technology transfer that will be need to support and operate the aircraft and has admitted that this will "test the boundaries of the US national disclosure policy."
This is disclosed by the Financial Times this morning, which identifies the core of the problem as US arms export laws, that mean the US will only disclose technologies only once Britain needs them.
During the development phase of the JSF, this has not been an important problem but, next year, however, the British government has to decide whether to buy the aircraft, putting as much as £2.6bn ($4.9bn) for 150 aircraft at risk.
Since the aircraft will not go into service until early next decade, Britain will not know for years whether the US will eventually grant it access to the core software codes it says it needs.
British officers are worried. "With any airplane in my inventory, I need the capability rapidly to modify for different circumstances, whether it be its software or hardware," says Air Chief Marshall Sir Brian Burridge, head of the RAF's fighter force. "We need the intellectual understanding close at hand so we can do that."
Bruce George, an MP and head of the British parliament's defence committee, says: "It seems to me truly absurd for a country like the UK, which has proved itself to be by far and away the most loyal ally to the US, to be in the position of almost grovelling to the US and saying, 'Please will you give us the information we require'."
The JSF’s builder, US aerospace giant Lockheed Martin, is equally concerned. Its programme manager, Tom Burbage, knows that the US wants the British to commit to buy the aircraft, and concedes that "the US is going to have to give some reasonable guarantees that the countries that buy the airplanes are going to be able to maintain them." "Right now," he adds, "that's not in the agreement."
And of course, the crunch point is here is China - as my colleague points out in her posting below - and the potential lifting of the EU arms embargo and the US concern over the security of defence technology once it is passed to Britain.
If the UK goes along with the French and German ambitions, negotiations may be much more than "thorny" and there is a very real possibility that the current problems that the UK is experiencing over technology transfer will seem minor by comparison.
Since the JSF is central to Britain’s future defence strategy – not least because it will equip the two planned aircraft carriers – once again Britain is putting its national interest at risk – to say nothing of the "special relationship" – all to keep in with our European "partners".
With over £2 billion of investment at stake, this is not a good bargain.