Justin Bieber on US Homeland Security watch list, he will be frisked every time he enters US

Justin Bieber's days of breezing in and out of the U.S. are over after he was added on US Homeland Security watch list for his two ongoing criminal cases. This means he will be searched indefinitely by U.S Customs every time he enters the states, TMZ reports.When Justin flew into a New Jersey airport from Canada last Friday... U.S. Customs searched his plane and then grilled him for hours, before letting him leave. Law enforcement sources tell TMZ ... Custom's flagged Bieber because he's on a Homeland Security watch list.

We're told Bieber is subject to the exact same treatment every time he leaves and then re-enters the U.S. -- a thorough search and then exhaustive questioning. 

It's very hard to get off the watch list once you're on it. You can appeal to Homeland Security but the agency has broad discretion.  What's more ... if Bieber is found guilty or pleads no contest to any criminal charge, it will be extremely difficult for him to go under the radar again.

As for whether that will cramp his style ... Bieber sources say he just doesn't care. "He's gonna do what he wants to do." says another source.