In his government’s defence review he is expected to slash the number of army troops by 7,000 and scrap the iconic Harrier jump jet.
However, he will argue that the changing national security landscape means that the billions saved on defence spending will not leave the UK vulnerable.
According to the National Security Strategy released yesterday, the most high priority security risks facing the UK are now terrorism, cyber attacks and natural disasters.
This means stockpiles of traditional military hardware such as tanks and fighter jets could eventually become superfluous to requirements.
Altogether the defence budget will be cut by around eight per cent over the parliament. This is compared to 25 per cent in most government departments.
The coalition is expected to give the go-ahead to a £5.2bn programme to build two new aircraft carriers. However, for up to eight years there will be a “capability gap” where there will be no available jets for the first carrier. Cameron will put this down to Labour’s legacy of debt and poor management of military contracts.
There will also be more cooperation with British allies, especially the French, who will be granted limited use of the aircraft carriers and take part in joint training exercises.
Cameron said: “Our objectives are a secure and resilient UK. Our national interest requires our continued engagement in world affairs, promoting our security... and our values.”