Justin Bieber was detained at LAX after flying back to the U.S. from Asia on Thursday. He was being questioned by U.S. Customs officials for at least two hours in the Tom Bradley International Terminal upon landing from a flight on Air Singapore.

It’s unclear why Bieber was being held for questioning and a spokesperson for U.S. Customs and Border Protection would not give any information about the incident.

The spokesman would only tell E! News "our CBP officers are charged with enforcing not only immigration and customs laws, but they also enforce over 400 laws for 40 other agencies and have stopped thousands of violators of U.S. law."

After Bieber’s Jan. 23 arrest for DUI, resisting arrest and driving without a valid license, he has left the country. However, according to TMZ, he’s now a target for U.S. Customs officials because his name is on the Homeland Security watch list for two uncompleted criminal cases.

Also in January, his private plane was detained at Teterboro airport in New Jersey because law enforcement believed there was a strong smell of marijuana on the plane.