Union leaders were today seeking urgent talks with defence giant BAE Systems after news that the firm is planning to axe 3,000 jobs in a "hammer blow" to the industry.
Unite said it wanted to clarify which sites will be hit by the jobs cull and would press for redundancies to be voluntary.
Ian Waddell, Unite's national officer for aerospace, said: "These job losses will be a hammer blow to the UK defence industry, which is already reeling with the consequences of the Government's "buy off the shelf" policy.
"We will be seeking urgent talks with BAE Systems to try and clarify where these jobs are under threat and to work with them to avoid compulsory redundancies wherever possible."
The facilities expected to be worst affected are BAE's military aircraft division in Warton, Lancashire, and Brough, East Yorkshire.
Shadow defence secretary Jim Murphy said the news was "a devastating blow for Lancashire and Yorkshire and a real knock for UK manufacturing", adding: "We need a fast response from ministers with a clear plan of action.
"At a time when it is so hard to find a new job this is a dreadful moment to lose the one you have.
"The defence industry is vital to the UK, supporting both our Forces on the frontline and the wider UK economy.
"Labour's industrial strategy has been replaced with this Government's deficit reduction plan and as a result both our industrial base and our equipment programme are being hit."
A BAE spokeswoman said: "BAE Systems has informed staff that we are reviewing our operations across various businesses to make sure the company is performing as effectively and efficiently as possible, both in delivering our commitments to existing customers and ensuring the company is best placed to secure future business
"As the outcome of this review becomes clear, we will, as always, communicate to our employees as a priority."
Earlier this year BAE Systems said around 2,000 workers would leave voluntarily or move to other jobs in the company, but there will be 450 compulsory lay-offs at several military sites across the UK, including Woodford, near Manchester, Farnborough in Hampshire, RAF Kinloss in Scotland, RAF Cottesmore in Lincolnshire and Brough in East Yorkshire.
The cuts were blamed on decisions such as the scrapping of the Nimrod and the accelerated retirement of the Harrier aircraft.
After the announcement in March, union leaders blamed the Government, with Unite claiming jobs were being lost as a direct result of Government decisions in last year's defence review, which led to the company warning of almost 2,500 posts being cut.
GMB national officer Keith Hazlewood said: "There were indications that there might be more job losses at BAE on top of the redundancies that have already happened but I am shocked by the scale of these cuts.
"This is a devastating blow for these communities, for the aerospace sector and for UK manufacturing.
"Workers and their families are still paying the price for the bankers' recession which started in 2007 and the recovery from it has stalled as these cuts show. Unions will be seeking urgent meetings with the company on this."