Hundreds of troops are being trained to drive ambulances and firefight in the event of strike action, the Government has said.
About 2,000 military personnel, civil servants and other volunteers from across the Government have been preparing as ministers brace for a wave of industrial action across the public sector.
The Cabinet Office said they included up to 600 Armed Forces personnel and 700 staff from the Government's specialist Surge and Rapid Response Team, as well as other parts of the Civil Service.
As well as covering for fire and ambulance crews, they could also be drafted into ports and airports in the event of strike action by Border Force staff.
Conservative Party chairman Nadim Zahawi said ministers were determined to minimise disruption from industrial action in the weeks ahead.
"It is the right and responsible thing to do to have contingency plans in place," he told Sky News's Sophy Ridge On Sunday programme.
"We have a very strong team at Cobra (civil contingencies committee) who are doing a lot of the work in looking at what we need to do to minimise the disruption to people's lives."
The Cabinet Office said no decisions have been taken yet on the deployment of troops, but they were part of the "range of options available" should the strikes go ahead as planned.
"The priority over the coming weeks is to protect the public who may need access to emergency services support, and limit disruption as much as possible, particularly at a time when increased numbers of people will be travelling for the festive period and NHS services are under huge pressure due to the impact of Covid," it said.
The measures come as a series of unions across public services are preparing to carry out strike action or ballot their members over pay as they seek to alleviate the squeeze on living standards from soaring inflation.
As well as ambulance staff, nurses in the NHS are due to hold two days of strikes this month while junior doctors are also set to be balloted on industrial action.
There is expected to be widespread disruption to transport in the run-up to Christmas with further rails strikes, walk-outs by baggage handlers at Heathrow and possible action by Border Force staff.
First reported by the Times, the Government could utilise the Military Aid to the Civil Authorities (Maca) to keep key services in the NHS running during major walkouts.
Maca was used during the coronavirus pandemic to help struggling health staff, with personnel supporting hospital and ambulance workers.
Armed Forces personnel were also used to carry out testing, administer vaccines and deliver protective equipment.
Last year, military personnel took part in training at Maindy Barracks in Cardiff to drive ambulances for the Welsh Ambulance Service NHS Trust (WAST).
A total of 100 service members from across the Royal Navy, British Army and RAF went through the training and worked alongside fully trained paramedics and technicians until November 2021.
The deployment followed a Maca request from WAST, as part of efforts to free up emergency responders under strain due to the pandemic.
At the start of the year, about 2,100 personnel were deployed across the UK to support emergency services.