New rules on all US-bound flights are set to come into effect, including stricter passenger screening to comply with government security measures.
The move is designed to avoid expanding an in-cabin ban on laptops.
Airlines say the new measures, which could include short security interviews with passengers, would be in place by Thursday.
They will affect 325,000 airline passengers on about 2000 commercial flights arriving daily in the US, on 180 airlines from 280 airports in 105 countries, and industry trade group Airlines for America has said the changes might cause disruptions.
The US announced the new rules in June to end the government's restrictions on carry-on electronic devices on planes coming from 10 airports in eight countries in the Middle East and North Africa in response to unspecified security threats.
Those restrictions were lifted in July but the Trump administration said it could reimpose measures on a case by case basis if airlines and airports did not boost security.
European and US officials told Reuters at the time that airlines had 120 days to comply with the measures, including increased passenger screening.
The 120-day deadline is Thursday. Airlines had until late July to expand explosive trace detection testing.
Lufthansa said on Tuesday the measures would be in place by Thursday and travellers could face short interviews at check-in or at the gate.
Economy passengers on Lufthansa's Swiss airline have been asked to check in at least 90 minutes before departure.
Cathay Pacific said it would suspend in-town check-in and self bag-drop services for passengers booked on direct flights to the US.
The airline said passengers would also have short security interviews and it has advised travellers to arrive three hours before departure.
US authorities in June also increased security around aircraft and in passenger areas, and other places where travellers can be cleared by officials before they depart.
Then Homeland Security secretary John Kelly said at the time the new rules require "more thorough passenger vetting, and new measures designed to mitigate the potential threat of insider attacks".
The Transportation Security Administration said in July it was imposing new security rules requiring US domestic airline travellers to remove all electronic items larger than mobile phones such as tablets, e-readers and video game consoles from carry-on baggage for screening.
Reuters
