Union leaders at BAE Systems have warned the huge job losses could leave the country without the skills to build its defence force and the region with a huge hole in the economy.
They were speaking after BAE Systems announced almost 2,000 jobs are to go across the country in its military, maritime and intelligence services under moves to streamline its business and have a "sharper" competitive edge.
The move came as a result of a slowdown in the orders for Typhoon and the Hawk fast jet trainer.
Union officials said in Lancashire Warton and Samlesbury were looking at 745 job losses. The manual worker population at the two sites are set to lose 347, the professional workers 326 and the executive side 72.
They said they wold be sitting down with bosses to discuss the consultation period for redundancies with the hop of avoiding compulsory redundancies and of mitigating some of the job losses.
Manual union convener at Warton, Bob Homes said that although job losses had been expected for a while they were shocked at the scale of the announcement.
He said: "There is an air of frustration and disappointment and, of course, uncertainty about what the future holds, but as a trade union we will be doing anything we can to help.
"We have traditionally had a good relationship with the management and a good record of working together."
He said that the national unions Unite and the GMB would be pressing the Government to act and he added that the country needs to commit to designing the next generation fighter for the future.
He added: "The problem with collaborating with other countries on aircraft projects is that they want us for our knowledge and engineering know how, but they then want to have manufacturing in their country which leaves us with very little for the future.
His words were echoed by union convener at Samlesbury, Roland Entwhistle who said it was vital to retain a skills base within the only company in the country capable of building a fighter to protect our shores.
He said: "There are 1,800 manual workers across both sites and the job losses amounts to almost 20 per cent of those workers, which is extremely concerning.
"This is the first time ever that this country has not had a next generation fighter on the drawing board. Countries are moving away from unmanned aircraft back to 6th generation manned aircraft but the Government has not committed to wanting one.
"That's fine if there is no future need, but there obviously will be a need. We will end up having to buy off the shelf from other countries for our defence needs. This is about sovereignty, about creating our own defence equipment and not relying on foreign powers.
"We are concerned that if we lose these manufacturing skills in Warton now, if more orders come in we won't be able to fulfil them. We will lose those skills and those well paid jobs which will have a knock-on effect on the local economy through the loss of taxes, the loss of spending power. For every one job at BAE there are up to six in the supply chain which will be affected."