The Home Secretary has urged Brits to rethink Christmas travel plans as she warned of "undeniable, serious disruption" if border strikes go ahead.
Suella Braverman said people planning to travel abroad need to "think carefully" about their plans as airports brace for festive chaos when Border Force, passport and visa staff walk out.
The Public and Commercial Services (PCS) union announced strikes on December 23, 24, 25 and 26, as well as 28, 29, 30 and 31 at Birmingham, Cardiff, Glasgow, Gatwick, Heathrow and Manchester airports, as well as Newhaven port.
Around 1,000 workers wiLL walk out on those days following a dispute over pay - with union leaders slamming the Government for refusing to budge on measly pay hikes.
Ms Braverman told broadcasters: "It's very regrettable that they have made this decision to potentially strike over critical times in the run up and following Christmas as the New Year.
"If they go ahead with those strikes there will be undeniable, serious disruption caused to many thousands of people who have holiday plans.
"I really want to urge people who have got plans to travel abroad to think carefully about their plans because they may well be impacted.
"We've got plans in place that will involve, to a degree, bringing in some of our military colleagues to help us in a variety of roles.
"Ultimately I'm not willing to compromise on security at the border, that's the number one priority.
"That may well have an adverse impact on convenience for people, frankly, whether it's the time they have to wait for flights, or departures, they may well be delayed on arrivals and various travel plans.
"Ultimately security at the border is my number one non-negotiable priority."
Downing Street said people should prepare for disruption.
The PM's official spokesman: "We would encourage anyone looking to fly to speak to the airline... because sadly there will be disruption. We want to be upfront that passengers should prepare for their plans to be disrupted."
PCS General Secretary Mark Serwotka warned that the union would escalate industrial action if no progress is made over pay.
He said: "The Government can stop these strikes tomorrow if it puts money on the table.
"Like so many workers, our members are struggling with the cost-of-living crisis. They are desperate.
"They are being told there is no money for them, while they watch ministers giving out Government contracts worth billions of pounds to their mates."
The PCS has previously said that 40,000 of its members employed by the Government rely on foodbanks and 45,000 claim in-work benefits.
More than 100,000 PCS members have voted to strike - with more government departments expected to be affected by strikes in the New Year.
