Passengers that fly in or out of SFO will see added security measures. Publicly, TSA is not asking U.S. airports to do anything different as far as security, but SFO is stepping up security for its travelers.
Police officers are patrolling terminals, a visible sign of heightened security.
"Anything they need to do is good with me" said traveler Dianne Kavanugh.
There are canine units, officers and even San Francisco's city's Tactical Unit. SFO made the move to bring them in, after an attempted Christmas Day terror attack on a U.S. plane.
The flight was from Amsterdam to Detroit, and the passenger when questioned by the feds said he tried to blow up the plane.
"It's just spooky to think that there was someone on the flight, being able to get on that flight and then ignite something during the plane trip," said traveler Barbara Doyle.
It's unknown how that passenger went undetected through Nigeria and Amsterdam airport security systems.
ABC7 Aviation Expert Ron Wilson said internationally, there are loopholes in security.
"Your security here at San Francisco or at any other airport is dependent upon the security of the country you came from and the city you came from," he said.
Passenger Ron McLaughlin agrees. He flew out of Korea on Saturday where security was a breeze. Then, he landed in Beijing.
"When we landed in Beijing, wow, every five seconds you were talking to a security person. They had tons, it was very impressive," he said.
Extra screenings at European airports forced some flights to arrive an hour late at SFO.
"It was much longer than expected in Frankfurt," said Arne Granhold, who was traveling from Frankfurt, Germany.
Even with the precautions and high tech technology, experts say detecting explosives on board is still the big hole in the system. It is slow and time consuming and they say the best bet to date for speed and accuracy is still on a leash.
"They are still [dogs] 96 to 97 percent effective on discovering explosives of all kinds," said Wilson.
Air Canada and other airlines are issuing new rules that they claim come from TSA. They include passengers not being allowed to get up and out of their seats, access their baggage or have anything on their laps one hour before landing at an airport, but TSA is not commenting on those rules.