Workers at the Atomic Weapons Establishment (AWE) are to launch a fresh 48-hour strike in a long-running dispute over pensions.
Members of Unite will mount picket lines at AWE's two sites at Aldermaston and Burghfield in Berkshire on Monday and Tuesday, following a previous stoppage earlier this month.
The union claims "iron-clad promises" made in the early 1990s by the then-Tory government to AWE workers regarding the future of their pensions once they transferred to the private sector have been broken.
Unite regional officer Bob Middleton said: " Confidence is high that we can win this dispute and see justice done.
"We need to maintain the pressure on the Ministry of Defence, so our members are given the opportunity to rejoin the MoD's principal civil service pension scheme.
"Once again, we call upon Defence Secretary (Sir) Michael Fallon to honour those pension pledges made 25 years ago."