Workers who maintain weapons for the Royal Navy's Faslane-based Trident submarine fleet are threatening strike action in a dispute over pay.
About 70 employees for the ABL Alliance at Royal Naval Armaments Depot Coulport could down tools on 16 and 20 December if their demands are not met.
More action could take place next year if the ABL Alliance refuses to meet the 3.8% pay claim made by the Unite Union.
The ABL Alliance – a joint venture by companies Atomic Weapons Establishment, Babcock Marine and Lockheed Martin UK Strategic Systems – signed a 15-year contract with the Ministry of Defence (MOD) to maintain weapons systems on the Clyde in 2013.
Union leaders have accused the ABL Alliance of 'dragging their feet' over the pay offer – which was made in July.
Unite general secretary Sharon Graham said: "For months now these extremely profitable companies have dragged their feet over giving our members the fair pay award they deserve.
"Unite's priority is to fight for the jobs, pay and conditions of our members, and these highly skilled workers at Coulport and Faslane naval bases have the union's full support in this dispute."
Stevie Deans, Unite regional co-ordinator, added: "The ABL Alliance employers have completely disrespected, undervalued and underappreciated our members.
"Unite has continually sought to resolve this pay dispute but the ABL Alliance at every stage of the process have seemed determined to force an escalation.
"Our members have been left with no choice but to take strike action in addition to the overtime ban, and we are determined to get the pay rise these workers deserve."
A MOD spokesperson said: "The Government is aware of the ongoing pay negotiations between the ABL Alliance and the Unite Trade Union; we are hopeful that a resolution will be reached by all parties.
"The continued safe operation of HM Naval Base Clyde is of paramount importance and the safe management of the port will not be compromised."