Nearly 2,000 jobs are to be cut in a shake-up of defence repair and maintenance services.
Dara engineers examine the cockpit of a jet
The Defence Aviation Repair Agency's (Dara) fast-jet site in St Athan, south Wales, will close with 500 job losses, armed forces minister Adam Ingram said.
Dara's engine maintenance business in Fleetlands, Hampshire, will also be shut with 225 jobs going by March 2007.
A further 1,226 jobs are being axed at Army vehicle repair service, Abro, with 628 of them going in Shropshire.
Abro will be closing its armoured vehicle and engine facilities at Donnington by March 2007.
Its "one-stop shops" at Warminster, Wiltshire, and Colchester, Essex, will also close by March 2007 with up to 281 posts lost, the minister told MPs.
A further 107 jobs will be shed at Bovington, Dorset, with up to 210 across other Abro sites, Mr Ingram said.
But 165 new Abro jobs will be created at a number of smaller facilities near Warminster and Colchester.
On top of the job losses, Dara's helicopter repair businesses at Fleetlands, in Hampshire, and Almondbank, Scotland, are to be market tested for possible sell-off.
Dara was set up in 1999 and is a civilian arm of the Ministry of Defence created to cut the costs of maintaining and repairing the UK's military aircraft.
Mr Ingram said the changes would save £2bn by 2010-11 and would significantly enhance the required frontline readiness of vehicles and aircraft.
He said that consolidating support for fast-jet and helicopters alone would produce savings of £70m over the next four years and a further £40m thereafter.
And he highlighted plans to transfer large aircraft business to the St Athan site, with the creation of around 350 jobs.
Mr Ingram said every effort would be made to make use of natural turnover and voluntary redundancies at affected sites, but admitted a "significant number" of compulsory redundancies were inevitable.
Amicus general secretary Derek Simpson said the decision to close Dara was "absolutely disgraceful".
"It is a total waste of taxpayers' money and will potentially put our armed forces in jeopardy."
There had been no proper consultation with the unions over the announced closures, he said.
The Defence Select Committee, which is currently investigating the decision to remove work from Dara, had not had a chance to report, he added.
"This is an absolute slap in the face to Parliament and MPs and to our highly skilled members who face being thrown on the scrapheap for what we believe are political, not economic or strategic military reasons."
Before the announcement, Transport and General Workers Union national officer Peter Allenson expressed "severe disappointment" at the expected cuts.
MP for Cardiff North Julie Morgan said the closure of Dara's St Athan plant was a huge loss for the area and that workers there felt betrayed.
Labour MP for Bridgend Madeleine Moon said it was a "dark day" for many families in her constituency and that hundreds of workers would be left "incoherent with resentment and anger".