The new measures came in the wake of the botched Christmas Day bombing of a Northwest Airlines plane heading from Amsterdam to Detroit which has forced many airports and airlines to boost already tight security.
All passengers flying into the United States from abroad will be subject to random screening or so-called "threat-based" screens, the Transport Security Administration (TSA) said in a statement.
But it further mandated that "every individual flying into the US from anywhere in the world traveling from or through nations that are state sponsors of terrorism or other countries of interest will be required to go through enhanced screening."
The tough rules go into effect from midnight on Sunday (0500 GMT Monday) and follow the failed plane attack blamed on a 23-year-old Nigerian who had recently travelled to Yemen to train with Al-Qaeda.
Suspect Umar Farouk Abdulmutallab reportedly boarded the flight at Amsterdam's Schiphol airport after flying in from Lagos, Nigeria.
Cuba, Iran, Sudan and Syria are currently the only four countries designated state sponsors of terrorism by the State Department.
But a senior administration official said the mandatory stringent measures, which would include pat-downs and enhanced screening, would apply to all passengers traveling from or via a total of 14 countries, including Afghanistan, Libya, Nigeria, Pakistan, Somalia and Yemen.
He refused to reveal the remaining four nations on the list but The New York Times and Washington Post quoted government officials naming them as Algeria, Lebanon, Saudi Arabia and Iraq.
According to US prosecutors, Abdulmutallab tried to bring down the Northwest Airlines Airbus A330 using a device containing the explosive PETN, also known as pentaerythritol.
Stitched into his underwear, it was not spotted by the traditional metal detectors. It failed to go off properly, but sparked an on-board fire put out by passengers.
Dutch officials have said they now plan to put full-body scanners into use within three weeks, and British Prime Minister Gordon Brown said Sunday British airports were also going to gradually introduce such equipment.
"We have recognized that there are new forms of weapon that are being used by Al-Qaeda so we've got to respond accordingly," Brown said.
Britain has called for a top conference on dealing with the terror threat from Yemen to be held in London on January 28.
US President Barack Obama, who vowed to act swiftly to close any security gaps, has accused Al-Qaeda in the Arabian Peninsula (AQAP), a Yemen-based cell of Osama bin Laden's group, of targeting the Northwest jet.
But amid questions over the failures in US security, Obama's top counter-terrorism advisor John Brennan said there had been no evidence which would have unmasked the plot sooner.
"There was no smoking gun. There was no piece of intelligence that said this guy is a terrorist and is going to get on a plane... None whatsoever," Brennan told Fox News Sunday.
"It was a failure to integrate the bits and pieces of information."
The United States and Britain meanwhile closed their embassies in the Yemeni capital on Sunday, as Brennan told CNN there were indications "Al-Qaeda is planning to carry out an attack against (a) target inside of Sanaa, possibly our embassy."
But Brennan indicated to Fox News Sunday the United States was not opening a new front against Al-Qaeda in Yemen and has no plans to send troops there.
"I wouldn't say we're opening a second front. This is a continuation of an effort that we had underway, as I said, since the beginning of the administration," said Brennan.
He also told CNN the United States would continue to repatriate Guantanamo detainees to Yemen, with about 90 still held at the US military base in Cuba.
"Some of these individuals are going to be transferred back to Yemen at the right time and the right pace and in the right way," he said.
The terror scare has prompted Obama to order two reviews of intelligence and security operations, and he will meet with spy chiefs and top officials Tuesday to discuss the findings.
Meanwhile, the family of Abdulmutallab, who is the son of a wealthy banker, have said they will travel from northern Nigeria to Detroit to attend his arraignment due on Friday.
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