Seven military barracks are to close and more than 30,000 soldiers relocated to new bases across the UK as part of a restructuring of the army announced on Tuesday.
David Cameron will underline his commitment to fight the new threat from jihadists in the Sahel by flying to Algeria on Wednesday to hold talks with the country's prime minister, aimed at forging what he promises will be a tough and intelligent alliance against terrorism in north Africa.
Britain's armed forces are at risk of being "fatally compromised" by a sustained cyber-attack because the military is dependent on technology that has no proven back-up, MPs have warned .
Hostile foreign states have used cyberwarfare to attack and map the networks that are part of the country's critical national infrastructure, the government has admitted.
David Cameron is expected to rule on the scale and scope of the British military withdrawal from Afghanistan over the next two years when he chairs a meeting on Tuesday of the national security council.
The Labour party will warn on Wednesday that it can offer no guarantees that it will be able to reverse any of the coalition's defence cuts in light of Britain's tight public finances.
David Cameron has defended British arms sales to Gulf countries as "entirely legitimate" but insisted that the Arab spring was a positive development and there were no "no-go areas" in talks with autocratic allies who are fretting about changes elsewhere in the region.
Britain has begun tentative talks with China and Russia about setting up a hotline to help prevent cyber-emergencies from spiralling out of control.
A newly elected Labour government would seek to close the multibillion-pound hole in Britain's defence budget by imposing an unprecedented 10-year programme that would be subject to annual independent oversight.
David Cameron responded to Nato disarray over its approach to mentoring Afghan security forces by telling the cabinet that he plans a full-scale cabinet-level review of British policy in Afghanistan soon after the US elections in November.