Defence technology company QinetiQ is set to lose about 100 staff from sites in Worcestershire and Hampshire, it has been confirmed.
The company blamed upcoming defence cuts and "particularly challenging times" for the losses.
Union leaders expressed "alarm" at the plans, warning vital skills are being lost to the UK.
QinetiQ is a British company formed from the sell-off of a UK government research agency.
It currently employs about 6,000 people in Britain, mainly in Farnborough and Malvern. About 50 jobs are to go from each site.
Prospect union national officer David Luxton said: "QinetiQ has lost around 800 posts in the last 12 months. Skills cannot be turned on or off like a tap."
QinetiQ said a consultation with staff had begun on Wednesday, and total job losses would be just below 100.
A spokesman said: "We have no choice but to review our cost base... ensuring we are fully aligned with customer needs."