Labour has described news of 3,000 expected job losses at defence giant BAE Systems as a "devastating blow".
Shadow defence secretary Jim Murphy spoke out after it emerged the company was set to announce a fresh wave of redundancies.
The facilities expected to be worst affected are BAE's military aircraft division in Warton, Lancashire, and Brough, East Yorkshire.
The firm has previously warned it expected to further cut staffing levels and it has emerged up to 3,000 posts will go.
Mr Murphy said the news was "a devastating blow for Lancashire and Yorkshire and a real knock for UK manufacturing".
"We need a fast response from ministers with a clear plan of action," he said.
"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.