New security measures announced Sunday night by the Transportation Security Administration take aim at those traveling to the United States from abroad -- and specifically passengers who've passed through a country that may be less than friendly to the United States.
Immediately after the Christmas Day bomb attempt, the government ordered patdowns and extra luggage checks for all travelers on international flights to the United States.
Such extra scrutiny will now be virtually mandatory for passengers coming into the United States who hold passports from or who have traveled through countries that sponsor terrorism, or other so-called "countries of interest."
According to a senior administration official, those countries are Afghanistan, Algeria, Iraq, Lebanon, Libya, Nigeria, Pakistan, Saudi Arabia, Somalia or Yemen, or one of the following countries designated as a state sponsor of terrorism: Cuba, Iran, Sudan and Syria.
Many other passengers from abroad can also expect extra scrutiny on a random basis.
But some experts question whether those measures will close the gaps that allegedly allowed 23-year-old Nigerian Umar Farouk Abdulmutallab to bring a bomb on Northwest Flight 253.
"The biggest hole is that people get on board airplanes who should not get on an airplane without going through secondary screening, which is what happened [with the Northwest flight]," said Charles Slepian, a security expert with Foreseeable Risk Analysis Center.
A TSA official insisted the new rules "are a significant step forward from what was in place on Dec. 24.
The goal, of course, is to keep a potential terrorist off a plane in the first place. Abdulmutallab was in a terrorism database -- but not one that triggered extra aviation security checks. That is now likely to change.
"I think you may see different thresholds for what makes you a selectee or what makes you a no-fly," said Kip Hawley, a former administrator with the TSA. "Right now those are very, very limited. I suspect they will broaden those definitions."
The TSA is also buying more full-body scanners for use in the United States and adding air marshals to international flights. But what's critical, many experts said, is that tighter security at foreign airports be enforced.
Sen. Charles Schumer, D-N.Y., Sunday evening announced his own plan to close security gaps, saying: "It's at airports across the globe where terrorists are trying to slip through the cracks and attack us."
There are no big security changes in the works for those flying domestically -- the focus remains on passengers coming from overseas.
And as for that one-hour rule that allows pilots to decide whether passengers should stay confined to their seats for the last hour of flight, the government said that remains at the crew's discretion.