While we're on defence costs, the debate on the Strategic Defence and Security Review continues in the Commons today.
Bob Ainsworth, Labour's last Defence Secretary, has been on his feet expressing real concern about the loss of the Harrier jumpjet fleet and accusing the government of blowing £2bn by delaying the Trident replacement.
Ainsworth said: "The decision to delay the deterrent again was a decision made for political reasons, made for coalition reasons, not made for industrial reasons or for reasons of capability.
"That decision on its own, if you take it out, no matter what the Prime Minister tries to say to the House costs this country billions of pounds. In excess of a billion pounds, I would say probably £2 billion.
"So for the purpose of keeping peace in the coalition for the next five years we have thrown away something between £1 billion and £2 billion."
He then dropped a huge hint that Labour might reconsider its support of the deterrent.
"My own party may well as a result of that... have to look at whether we maintain our position on Trident."
He added: "then we are going to have to think seriously about whether or not there is another way... of maintaining Britain's deterrent, without the huge cost cutting expenditure on the rest of our armed forces."
When he was challenged by the Defence Secretary Liam Fox on his apparent change of position, Ainsworth said that if Labour did not examine its stance on Trident it would be seen as putting its head in the sand.