BARBRA STREISAND and husband JAMES BROLIN are at war over his son’s out-of-control drinking!

The 70-year-old singing legend exploded after learning that her stepson Josh Brolin was arrested on New Year’s Day for public intoxication – and now she’s demanding that James, 72, force Josh into rehab before he destroys his life.

“Barbra thinks that Josh has a drinking problem and needs help,” said a family friend. “She’s told Josh, ‘You’re killing yourself.’ But James told Barbra that his son is a grown man, and he refuses to get involved in Josh’s life.”

Josh, 44, was arrested just before midnight on Jan. 1, when officers in Santa Monica, Calif., found him heavily intoxicated on a sidewalk. He was booked into jail but released just seven hours later after sobering up. Santa Monica Police Lt. Darrell Lowe says the “Gangster Squad” star was not given a citation for the arrest, which means he likely won’t have to appear in court.

Although Josh got off lightly with authorities, Barbra is said to be livid. According to a friend, she’s afraid that if Josh doesn’t get help soon it could be curtains for his marriage to his actress wife Diane Lane, 47.

Josh has a long history of alcohol-fueled run-ins with the law.

“When I was 19, a fight broke out, and when the police came, I fought the police. I was pretty drunk,” Josh confessed in a recent mag interview.

“To this day, I have no idea what the fight was about. I woke up in jail. The police were very angry with me. Very angry. They kicked my ass really well.”

Josh went on to brag that he lost his virginity at the tender age of 11 and smoked heroin as a kid.

The troubling behavior continued into his adulthood. In December 2004, just four months after marrying Diane, he was arrested following a domestic dispute at the couple’s home.

Fortunately for him, Diane refused to press charges.

Then, in July 2008, Josh was arrested in Shreveport, La., along with a co-star and five other crew members on the film “W,” after an altercation at a local bar. Charges were eventually dropped.

But the recent arrest is the last straw for Barbra – and she’s insisting that James step in and get Josh into rehab.

“Barbra just doesn’t understand why James is not as upset about Josh’s drinking problem as she is,” said the friend. “She thinks James should act like a responsible parent no matter how old his son is – and James has told Barbra to ‘butt out’ and let Josh and Diane work it out on their own.

“James doesn’t want to get involved with his son’s personal life, but not getting involved is causing problems in his own marriage. He’s in a no-win situation. No matter what he does, it’s going to make someone angry.”