BAE Systems and Rolls-Royce have outlined plans to cut staff.
Defence giant BAE Systems said up to 371 jobs will go as the group slows production of its Typhoon jet fighters.
The vast majority of the job losses will affect the 13,000-strong workforce in Samlesbury, Lancashire, although some roles will also be impacted in its Typhoon final assembly production team.
BAE said it hoped find opportunities elsewhere in the business for staff in an effort to limit the number of compulsory redundancies.
Engine-maker Rolls-Royce announced it would be "streamlining" its senior management next year.
The firm has around 2,000 staff in that category. It is not clear how many are at risk, but the cuts will not be limited to its UK operations.
The announcement forms part of a broader restructuring programme, which Rolls-Royce chief executive Warren East hopes will save the firm around £150 million to £200 million a year.
"The next few years are going to be important in laying the foundations for our long-term profitable growth," he said.
"Therefore it is important to ensure we are financially stronger, more resilient to short-term shocks and more flexible to take advantage of growth opportunities."
It comes as the engine-maker downgraded its profits forecast for next year again.
Mr East warned the firm faced profit headwinds of around £650 million next year, significantly higher than the £300 million cut outlined in July.