Just when airline passengers were getting used to life in the post-9/11 world, Abdul Farouk Umar Abdulmutallab threw airport security on its head. He is the one who allegedly tried to blow up a Northwest Airlines plane on Christmas day.
Now travelers looking to fly are faced, yet again, with a new set of rules and procedures and are once again struggling to figure out how life at the airport has changed.
The Transportation Security Administration has not publically spelled out all the security details (why share that information with the terrorists, right?) but has instead described its new procedures as a "layered approach."
But what does that mean? ABC News has tried to sort through it all and give you this guide on how air travel is different for you today.
Will You Notice Anything Different At Airports?
Not necessarily. There have been reports of some longer lines at security. And everybody is a bit more on edge these days because of the attempted Christmas attack, which can also mean it takes longer to clear the checkpoint. The TSA said that some of its measures are clearly seen by people while others might be hard to detect.
What Additional Steps Are Being Taken?
The TSA said it has the ability to "quickly implement additional screening measures," including explosive detection canine teams, extra law enforcement officers, additional screening at the gates, behavior detection and other unspecified measures.
Why Do Some Airports Handle Security Differently?
The basics of airport screening -- you know, take off your shoes, remove your laptop and jacket and walk through the metal detector -- remain the same. But the TSA warns that passengers should not expect to see the same thing at every airport. That warning generally refers to the extra measures such as additional gate checks or canine teams. What About International Flights?
Immediately following the Christmas Day attack, the government required all passengers on international flights to stay seated for the final hour of the journey and have nothing on their laps. The government has since relaxed that rule, leaving it up to individual flight crews, for now, to determine what rules to impose on passengers.
Do International Travelers Face Additional Requirements?
Yes, this week the TSA started requiring all passengers on flights from certain countries to go through an "enhanced screening" process. Some international passengers told ABC News that they underwent thorough bag searches and were patted down.
The TSA is only requiring such searches for people who are "traveling from or through nations that are state sponsors of terrorism or other countries of interest." A senior government official told ABC News that those countries are: Afghanistan, Algeria, Iraq, Lebanon, Libya, Nigeria, Pakistan, Saudi Arabia, Somalia, or Yemen, or one of the following countries designated as state sponsors of terrorism: Cuba, Iran, Sudan, and Syria.
Have the Allowed Carry-On Items Changed?
No. The TSA says that for passengers departing U.S. airports the security checkpoint requirements remain the same.
Should Passengers Arrive at the Airport Earlier Than Normal?