Defence Secretary Philip Hammond announced a change in the choice of fighter aircraft for the Royal Navy's new aircraft carriers, arguing that the move was part of an "affordable equipment programme".
In a statement to MPs on 10 May 2012, Mr Hammond said the government had taken defence policy decisions in the light of "the black hole in Labour's defence budget and the unaffordable, fantasy equipment plan bequeathed to us by the party opposite".
The coalition had previously endorsed the decision to equip Britain's carriers with F-35 joint strike fighters, but is now poised to adopt a plan originally put forward by Labour to use the less capable jump jet model.
Under the 2010 Strategic Defence and Security Review (SDSR), the coalition had planned to switch to the F-35C - arguing it was a more capable aircraft and, unlike the F-35B jump jet, would be inter-operable with the US and French navies.
Mr Hammond told the Commons that the SDSR decision was followed by a study of the "costs, risks and technical feasibility" of the plan.
However, he said, that the costs of fitting the necessary catapults and arrester gear - "cats and traps" - to one of the carriers while the other ship was mothballed had subsequently risen over the last 18 months to almost £2bn.
The defence secretary said that abandoning the plan meant that both carriers, HMS Prince of Wales and HMS Queen Elizabeth, could eventually become operational.
He insisted that ministers had discussed the move with the governments of the US and France and claimed that US Defence Secretary Leon Panetta endorsed the decision.
Shadow defence secretary Jim Murphy said: "When the government do the right thing on defence, they will have the support of these benches."
Referring to the recent local elections, Mr Murphy joked that the move "must be the first example of waiting until the polls close to announce good news".
He accused the government of "incompetence" and added: "The previous Labour government got it right and this government's policy has unravelled."