Lord Drayson, the defence procurement minister, told a specially convened Congressional hearing here that the UK would have serious concerns about sharing information on the JSF if the second engine was dropped.
Britain had not been consulted on the proposed changes in the programme. "Without the technology transfer to give us aircraft that are fit to fight on our terms, we will not be able to buy this aircraft," he warned the Senate Armed Services Committee.
The stealth-equipped JSF, or F-35, is the single largest defence programme ever, costing up to $250bn and involving eight countries. Britain was the first US ally to sign up to the programme, committing to buy some 100 planes. The quid pro quo, however, was Rolls-Royce's involvement in the back- up engine.
The decision to drop the second engine, announced last month as part of the fiscal 2007 Pentagon budget, caused anger and resentment in London, and was widely taken as another sign of US indifference to the interests of its most loyal and important ally in the Iraq war. Late last year Tony Blair has intervened in person with President George Bush - but to no avail.
The move would cancel a $2bn (£1.3bn) research and development contract signed in 2005 by Rolls-Royce and General Electric, its partner on the back-up engine. The main engine is being built by Pratt & Whitney of the US.
The committee chairman, John Warner, called the hearing because he opposes the cut, arguing that a notional saving of $1.8bn in 2007 took no account of potential quality improvements over the 30-year contract. A GE spokesman saidcompetition on the engine could save $12bn over the contract's life.Reuse content