How did Tal make into the U.S and into the CIA director's home without getting caught?

In the show The Enemy Within, the team is hunting down and trying to capture a terrorist named Tal. We see in flashbacks that Tal makes into the U.S and threatens Erica Shepherd, even going to her home and attempting to recruit her.

How does Tal enter the U.S without getting caught? We know the CIA stopped one of his planned attacks, so they're aware of him. The show takes place after 9/11, so we can assume security measures at the airport are the same as in real life.