Justin Bieber's return to the United States from Japan just came to a halt at the airport. He's being held up at LAX customs. It would seem that it involves the singer's recent legal issues.

Justin and his crew flew into LAX from Japan this afternoon, but his now infamous party van, his crew and all his luggage have been waiting out by the curb for over an hour.

Sources close to Bieber have said U.S. Customs agents are giving the Biebs a secondary customs search ... which includes looking further into all his open criminal cases... meaning the DUI arrest in Miami, egg throwing at his neighbor, and more.

It's supposedly standard operation for anyone with a record like Bieber's -- and doesn't mean he's getting arrested for anything. Keep in mind that he is not an American citizen (he's Canadian), so it is more difficult to pass through customs.

If more develops in this, we will keep you updated!