The United States announced Wednesday it would implement tough new security rules for all airlines flying into the country, but held off from a threatened expansion of its carry-on laptop ban.
Secretary of Homeland Security John Kelly said evolving terror threats made it imperative to raise overall security standards, rather than take a piecemeal approach on personal electronics.
"Make no mistake: our enemies are constantly working to find new methods for disguising explosives, recruiting insiders, and hijacking aircraft," Kelly said.
"We cannot play international whack-a-mole with each new threat. Instead, we must put in place new measures across the board to keep the traveling public safe and make it harder for terrorists to succeed."
The move put off for the moment an extension of the ban on laptops and other carry-on personal electronics to flights from Europe, something that had been under discussion for months.
The laptop ban was instituted in March for eight North African and Middle East countries based on intelligence that the Islamic State group was working to build a bomb into a tablet or laptop computer.
For the same reason, Britain also banned similar-sized electronics from being carried into cabins on direct flights from six countries.
In a speech at a conference of the Center for a New American Security, Kelly said the terror threat to airlines has not diminished.
"In fact, I am concerned that we are seeing renewed interest on the part of terrorist groups to go after the aviation sector -- from bombing aircraft to attacking airports on the ground, as we saw in Brussels and Istanbul."
He said airlines and airports around the world would have to implement a mix of new technological and physical screening methods for passengers and their devices.
- 2,000 daily flights in focus -
Homeland Security officials said the agency would issue directives to about 180 air carriers in 105 countries, including US carriers, that fly into the United States.
Collectively they operate about 2,000 US-bound flights each day carrying some 325,000 passengers.
Kelly also said the United States would push harder for foreign airports to accept "preclearance" immigration operations manned by US Customs and Border Patrol officials to process US-bound passengers before they board their flights.
Such operations have already been established in 15 locations in six countries, including Canada, Ireland and the United Arab Emirates.
But it raises sensitive sovereignty issues to have US law enforcement officials operate inside another country.
US officials remained vague about the specific requirements of the new program.
Airlines will be pressed to adopt a mix of new measures, including installing new screening technology, making more use of chemical sniffer dogs, and other unspecified steps.
But the precise requirements in each case would depend on individual airlines, the airports they fly from, and their current levels of security. Some will have to make only minor improvements, they said.
Asked about timeframes, officials would only say that they would give adequate time for the airlines to adapt.
"We are raising the bar globally" for security standards, said one senior official who declined to be identified.
They also said they expect nearly all carriers to be able to meet the new standards.
Those that cannot or will not, they said, would be forced to reject all passenger electronics, either in the cabin or hold of the aircraft, or may even find themselves unable to fly to the United States.