After the Conservative-Liberal Democrat coalition's first 100 days in office, the BBC's Defence Correspondent Caroline Wyatt writes that the coalition is in a difficult position on defence: "It inherited an unpopular war in Afghanistan, as well as a black hole in the defence procurement budget of some £37bn of equipment - ordered over the next decade without the guaranteed funding to pay for it."
An analyst quoted in the article warns that the SDSR may be constructed in such a way that the Armed Forces "will never be able to do an Iraq or Afghanistan again". Such an outcome would be popular in some circles, but it would also mean that UK forces could never play more than a very minor part in future operations like Bosnia, Kosovo or the 1991 liberation of Kuwait.
"The coalition inherited a defence budget that was over-committed," says Dr Paul Cornish, head of the international security programme at Chatham House.
"I think there is a possibility that the defence review will be constructed in such a way that after the SDSR, the Armed Forces will never be able to do an Iraq or Afghanistan again.
"In a way that is fine - as long as we don't have to do something like that again," he warns.
"But if there is a need to do something similar, we may then find ourselves in a pretty sticky position."
He says the choice facing the Ministry of Defence is stark, and will reshape the UK's Armed Forces in one of two ways: either producing balanced Armed Forces able to undertake a broad range of tasks and commitments, as in the past, or forces which specialise, but lose their broader capabilities.