BAE Systems is to axe around 1,300 posts, the company has announced.
The move, which followed the government's defence review and its decision to scrap the Nimrod and Harrier jets, was condemned by union leaders.
The job losses will hit a number of sites, including Samlesbury and Warton in Lancashire, Farnborough in Hampshire, Yeovil, RAF Cottesmore and RAF Kinloss. The company also revealed it would be consulting unions over potentially closing its Woodford site in Cheshire earlier than had been previously announced.
Kevin Taylor, managing director of BAE Systems Military Air Solutions, said: “Since the publication of the Strategic Defence and Security Review in October we have taken time to understand the implications for our business.
“We have recently received termination for customer convenience notices for the Nimrod MRA4 and Harrier contracts and this has regrettably led us to initiating consultation regarding potential job losses.
“Today's announcement is designed to ensure we remain competitive as we actively pursue a number of opportunities for our other products and services both in the UK and internationally.
“Military Air Solutions remains a sustainable business with a strong business plan. I appreciate this is difficult news for our people and we are committed to working with employees and their representatives to explore ways of mitigating the potential job losses."
Bernie Hamilton, national officer of the Unite union, said: “This is a tragedy for the workforce and for Britain. The coalition government's Christmas present to over a thousand skilled workers who support Britain's armed forces is the sack.
He added: “The country that gave the world the revolutionary Harrier jump jet will lose the know-how to build an aircraft like this. “BAE's workers are urging the Government to think again and reverse this decision. The coalition is denying the UK armed forces vital equipment to defend this nation while families across the country worry about their futures."
Keith Hazelwood, national officer of the GMB union, said: "This is a devastating blow for UK manufacturing and the local communities. GMB will be seeking detailed meetings with BAE Systems to see exactly where the axe is falling and what steps if any can be taken to mitigate these job losses.
"We have recently seen a number of developments where the skills of the workforce involved have been redeployed in terms of green and space technology and we will want to explore with the management if there is any scope for this."
BAE said: “Following a detailed review of the implications of the UK Government's Strategic Defence and Security Review, and in particular the impact on the Harrier and Nimrod programmes where we have now received contract termination for customer convenience letters from the Ministry of Defence, BAE Systems has announced it has started consultation regarding potential job losses at six of its UK sites and two RAF bases.”
The potential job losses will be 79 at Chadderton, Greater Manchester, 214 at Farnborough, Hampshire, 55 at Prestwick in Ayrshire, 119 at Samlesbury, Lancashire, 668 at Warton, Lancashire, 15 at Yeovil, Somerset, 127 at RAF Cottesmore, Rutland, and 30 at RAF Kinloss, Moray.
The total number of potential job losses announced today was 1,397, the company said.
BAE said that as a result of the cancellation of the Nimrod MRA4 programme, the consultation will also cover closing the Woodford site in Cheshire earlier than was previously announced, with the potential for hundreds more job losses.
The company announced in September last year that Woodford, which employs 630, would close at the end of 2012. No new date for the shutdown has been given.
At Chadderton, Prestwick, Yeovil and RAF Kinloss the potential job losses are associated with the cancellation of the Nimrod MRA4 programme, said the company.
At Farnborough and RAF Cottesmore, the cuts are associated with the early withdrawal from service of the Harrier fleet. Samlesbury and Warton have been hit by the cancellation for customer convenience of the Nimrod MRA4 programme and the early withdrawal from service of the Harrier.
In addition, BAE Systems Saudi Arabia launched a consultation with unions today on 90 potential job losses in its UK business, mainly at Samlesbury.