U.S. officials in Washington said the new security measures would be implemented Monday but there were few visible changes on the ground in Europe, which has thousands of passengers on hundreds of daily flights to the United States.
TSA Spokesman Greg Soule told CBS News, "We will continue to work with our airline and international partners to ensure that they meet both international and TSA security standards."
Large hubs such as London, Paris, Amsterdam and Frankfurt alone account for 20-30 trans-Atlantic flights a day each.
In Britain, a major international transport hub, a spokesman for the Department of Transportation said he was still trying to decipher the practical implications for Britain of the new U.S. rules. He refused to give his name due to the sensitivity of the subject.
U.S. authorities said as of Monday, anyone traveling from or through nations regarded as state sponsors of terrorism - as well as "other countries of interest" - will be required to go through enhanced screening. The Transportation Security Administration said those techniques would include full-body pat-downs, carryon bag searches, full-body scanning and explosive detection technology.
The U.S. State Department lists Cuba, Iran, Sudan and Syria as state sponsors of terrorism. The other countries whose passengers will face enhanced screening include Afghanistan, Algeria, Iraq, Lebanon, Libya, Nigeria, Pakistan, Saudi Arabia, Somalia and Yemen.
The new measures followed the arrest of a Nigerian man, Umar Farouk Abdulmutallab, who allegedly tried to set off an explosive device on a flight from Amsterdam to Detroit on Christmas Day.
Germany announced increased security at all airports following the failed Christmas Day attack, but authorities on Monday said no further measures have been taken since.
In Switzerland, authorities were studying the new U.S. security measures, but so far the old controls were still in place, said Jean-Claude Donzel, spokesman for Swiss International Air Lines.
And a security official in Spain, who spoke on condition on anonymity in line with agency rules, said U.S.-bound passengers from countries on the new watch list were not being singled out for body frisks.
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Elsewhere in the world, there has been a general ramping up of security since Christmas.
In Jordan, a key U.S. ally, security was beefed up at Amman's main international airport since the Christmas Day bombing attempt. An official at Queen Alia International Airport said "enhanced techniques" were being applied, especially in screening passengers bound for the United States. He declined to elaborate.
Pakistan's national airline said it was intensifying security checks for U.S.-bound passengers, even though there are no direct flights to the States from Pakistan. Screening was also stepped up for those flying to the U.S. from other parts of Asia and the Middle East.
"It is beyond my imagination what more they could do," said Nadim Umer, 40, a Karachi-based linen merchant who said he was subjected to a strip search when he arrived in New York last June. "Those who are dying to go to America at any cost can put up with all this inhuman behavior, but I cannot."
A spokesman for Pakistan International Airlines said the company began applying the new security standards Jan. 1 on U.S.-bound passengers.
Sultan Hasan said the passengers are subjected to special screening, including full body searches, in a designated area of the departure lounge. He said the airline had run advertisements in newspapers to warn prospective passengers of the increased safety measures. maintaining strict security standards at all airports for all flights.
"We are already carrying out all possible security arrangements at our airports which can be compared with any Western airport," Pervez George, spokesman for Pakistan's Civil Aviation Authority. "Safety of the airliners and passengers as well as security at the airports is a top priority and we are maintaining it irrespective where the flight is going."
In South Korea, an official at Seoul's Incheon International Airport, Lee Ji-hye, said U.S.-bound passengers are now required to go through additional security before boarding their flights, and security officials also compile lists of "suspicious" passengers to monitor based on their nationalities, travel patterns and ticket purchases.
Australian Transport Ministry spokeswoman Moksha Watts said all passengers flying to the U.S. would continue to be patted down and have all their cabin luggage searched.
Baghdad's International Airport already has extremely tight security, with passengers having their luggage sniffed by dogs and getting patted down before entering the airport.
"Our security procedures at the airport are more intensified than that in any other airport in the world," said security official Umran Idris.
Maayan Malkin, spokeswoman for Israel Airports Authority, declined to discuss security arrangements. The Ben-Gurion International airport is considered one of the safest in the world.