Although the Public and Commercial Services Union has yet to specify when it plans to take industrial action a spokesperson for the union told me that strike action during the Olympics was certainly a possibility.
They will be targeting border controls so that means airports and ports. Given the fact that they only have to give seven days notice the timing is clearly intended to hurt the government as much as possible.
The union have said that they are angry at various issues and in particular the fact that many jobs are under threat - up to eight and a half thousand - but I think the news has really taken the Home Office by surprise with one source there telling me it was "completely ludicrous" that strikes were even being considered, although they did tell me that they had contingency staff in place.
Downing Street too seem to be rather taken aback by the move.
Interesting though that in terms of support for this, only 20% of the union voted in the ballot, so many people may well say that the union leaderships don't have a mandate at all.