Aerospace giant BAE Systems is to axe almost 600 jobs at two of its military factories, unions have been told.
Officials expressed shock at the scale of the cuts at the sites in Brough, near Hull and Woodford, near Manchester.
Unite said it would resist compulsory redundancies among the 450 job losses at Brough, home of the Hawk aircraft, and 134 job cuts at Woodford, the home of Nimrod.
National officer Bernie Hamilton said: "Only a few days ago the Red Arrows had the Hawks on display to celebrate the RAF's 90th anniversary. Sadly, the future for the skilled workers that built these state of the art jets is now uncertain.
"Unite will resist any compulsory redundancies and will be working with management at both sites to find alternatives, including re-skilling, transfers to other operations and work packages from other projects.
"In the long term it is imperative that the aerospace industry and the UK Government reaches agreement to safeguard the UK's large fixed wing capability for future generations."
BAE Systems said the job cuts at Brough would affect engineering, manufacturing and business support areas, while those at Woodford would impact on engineers.
The company said it had been seeking additional work for the Brough site, but it was not able to sustain the current number of jobs. A transition plan was being developed to retain "critical capabilities" at Brough, which would include reducing its dependency on the Hawk.
BAE said a review last year of the engineering capabilities in its military air solutions business had identified that the workload would reduce as products moved from design and development into the support phase, which had led to the job cuts at Woodford.
The firm said there was no opportunity for significant transfer of engineering work packages to the site, despite the good reputation of the Woodford team.
