New security measures come into force on Thursday involving stricter passenger screening on all flights into the United States.
The new rules could involve security interviews at check-in or the boarding gate, as well as closer inspections of electronic devices.
The changes were announced in the summer after intelligence suggested terrorists could smuggle explosives into laptops. Airlines were given 120 days to comply.
“I think with European airport security, they are challenged because they can’t control as much access from one country to another, from border to border,” said aviation security analyst Jeff Price.
The new measures have sparked concerns over flight delays and increased processing time. Some airlines are asking passengers to get to airports earlier.
There has been some criticism of the rules especially from Asia.
US restrictions on carry-on electronic devices on flights from parts of the Middle East and North Africa were lifted in July, but the Trump administration said it could re-impose them on a case-by-case basis.