Defence Secretary Geoff Hoon has announced large cuts in the armed forces as part of modernisation plans.
Forces numbers will be cut
By 2008 the RAF will shed 7,500 jobs, the Navy 1,500 with a further 10,000 civilian posts also lost. Aircraft, tank and ship numbers will also be cut.
Flexibility and the ability to fight far from the UK is key, says Mr Hoon.
Tory Nicholas Soames said personnel would feel "betrayed politically and morally" and the public would be "dismayed" by "underhand" treatment.
For the Lib Dems, Paul Keetch said: "Iraq has shown that winning the peace needs more troops on the ground than winning the war."
He added "a bit of spare capacity would have been a good insurance policy".
Mr Hoon told MPs: "The threats to Britain's interests in the 21st
Century are far more complex than was foreseen following the disintegration of
the Soviet Empire.
"That is why the Defence White Paper signalled that we should continue to modernise the structure of our armed forces, to embrace new technology, and to
focus on the means by which our armed forces can work together with other government agencies to meet the threat of international terrorism and the forces
of instability in the modern world."
His view was shared by chief of general staff, General Sir Mike Jackson, who told BBC's Newsnight programme:"It's a very diffuse threat", ranging from conventional wars, such as in the Balkans, through to humanitarian crises, and the global terror situation since 11 September.
Mr Soames, shadow defence secretary, said he accepted the need for hard choices but said Mr Hoon's statement was essentially about cuts.
He said there was a a "deep crisis in the defence budget".
Among key measures planned are:
- RAF to shed 7,500 jobs and the Navy 1,500 jobs by 2008. A further 10,000 civilian posts across the armed forces will be cut.
- Four infantry battalions - three from England and one from Scotland - to be cut as part of the "restructuring".
- Three type-42 destroyers and three type-23 frigates taken out of service from the Royal Navy by March 2006.
- One RAF Tornado F-3 air defence squadron would be cut and the withdrawal of two Jaguar squadrons would be brought forward to 2006, with the final Jaguar squadron to be disbanded in 2007.
- RAF Coltishall in Norfolk will close by the end of 2006.
- The Navy will gain two new large aircraft carriers. The oldest destroyers - HMS Cardiff, Newcastle and Glasgow will be pensioned off by the end of next year. Three anti-submarine frigates - HMS Norfolk, Marlborough and Grafton will be pensioned off by 2006.
In a written message to service personnel, General Sir Michael Walker, chief of the defence staff, outlined just how many staff would go in the cuts.
"The numbers are stark - some 20,000 in total, broadly split between military
and civilian personnel," he wrote.
The details follow Mr Hoon's white paper Security in a Changing World, presented to the Commons in December.
The Ministry of Defence is planning to invest heavily in hi-tech digital systems to enable it to work closely with American forces.
But General Jackson told Newsnight: "We should be able to work with the United States Army - but that doesn't mean to say we have to work as they do.
"We are the British Army, we're not some sort of adjunct. We have our own style and way of doing things."
But there are concerns the "special skills" of the British armed forces could be lost in the shake-up which is being seen as one of the most radical they have undergone.
Labour chairman of the defence committee, Bruce George, asked: "Please explain who the idiot was who thinks you can cut the infantry at a time when the pressure on them is enormous?
"Has he (Mr Hoon) consulted Gerry Adams or maybe the Fire Brigades Union whether they are going to behave themselves over the next few years?"
Real term increases
Mr Soames said: "It's a very important thing to keep a balance between the manpower and the application of new technology.
VESSELS TO BE PENSIONED OFF
"What matters at the end of the day is the boots on the ground," he added.
Plans to cut six frigates from the navy would "seriously degrade the navy's ability to do its standing task", Mr Soames said.
The base commander at RAF Coltishall, Norfolk, spoke of sadness at news it would close.
Group Captain Graham Wright said: "The station has a fantastic history, from the Battle of Britain to the 30 years service of Jaguar, it is a history we are extremely proud of."
A spokesman for the Transport and General Workers Union said he wanted to know more details of the changes.
"The T&G has a significant membership across the military support services,
many of whom will not be resting easy tonight," he said.