Largest cut

The result is that Cameron is almost certain to announce on Tuesday that the SDSR will contain the largest cuts in the military budget and equipment since the end of the Cold War in 1990.

Tipped for the chop are some of the 23 frigates and destroyers currently in service with the Royal Navy, along with its amphibious assault capacity, carried in three large ships. The replacement for the navy's four-strong Trident submarine fleet which carries nuclear missiles, will certainly survive, as will the partially completed program to build two large aircraft carriers simply because it will cost more to cancel than the 5.2 billion pounds (8.1 billion U.S. dollars) to complete.

However the aircraft to fly from the carriers may not be ready for when they are launched, scheduled for 2016 and 2018, as cuts elsewhere in military spending will remove that current capacity before a new generation of American-built aircraft can be delivered.

The Royal Air Force looks likely to lose some of its jet aircraft, with its fleet of 75 Harrier jump-jets, capable of vertical take-off, looking favorite for early retirement. These are the jets capable of flying off a carrier, but look likely to be axed in favor of keeping the 190-strong fleet of Tornado aircraft, which cannot operate from carriers.

The army, currently committed to a war in Afghanistan with 10, 000 troops deployed, has argued it cannot take cuts of more than 5, 000 soldiers, but looks likely to lose many of its tanks and possibly its heavy artillery, which are mostly deployed in north Germany where they were stationed to combat a perceived threat from the Soviet Union before the collapse of the Berlin Wall in 1990.

In the NSS Cameron and Clegg all but identified this part of the army as ripe for the chop, "the equipment we have is still too rooted in a Cold War mind-set."

The government Monday was wary of appearing weak on military spending and Foreign Secretary William Hague stressed in a TV interview that at the end of the cuts Britain "will still have the third or fourth largest defense budget in the world, we will still be a global military power."

With the publication of the NSS, the coalition government and Prime Minister Cameron have prepared public opinion for military spending cuts that are considerably smaller than those which will be announced on Wednesday for other government departments, which in some cases could suffer cuts of up to 40 percent, but are still certain to shock and to draw criticism.

Cameron will be keen to avoid charges that his government is failing to adequately defend Britain, and having identified cyber- attacks as a serious future threat he is also expected Tuesday to announce an increase of several hundred million pounds in spending on countering the cyber threat.