Last month we saw scenes of long queues - what a welcome to the UK.
Now strikes will bring a new flashpoint in the battle over how Britain's borders should be run.
Yesterday at the port of Dover I met Peter Norris - a serving border officer for 30 years.
Whilst most are forbidden from talking to the media, his work as a union rep means he's determined to speak out. He says low staff levels mean checks are often "cut to the bare bone."
While queues at Heathrow have been shrunk, he says busy ports like this have paid the price -with worrying consequences.
He says "history shows if we drop our guard, criminals will move in."
Today's strike lay bare a long running dispute, border unions say their pension contributions will in some cases triple to 5.7% with the retirement age rising to 67; with pay already frozen and a maximum rise of only 1% for two years.
On staffing: they are concerned 1,500 posts will go by 2014.
Today, border managers will use a trained pool of backroom staff and MOD police as cover.
The union says vital work will be neglected and told us an internal email from one regional airport told staff, "there will be no freight examinations conducted."
But airlines I spoke to believe the government plan is adequate.
Officials last night insisted they will secure the border against illegal immigration and smuggling.
Longer term, government believes it can balance the need for cuts with maintaining security.
But the stakes are high ahead of a summer where the world is queuing up to visit Britain - nobody wants the queuing to literally be the case.