THE U.S. Marine Corps is a storied fighting force, but lately it has done a huge favor to the nation’s enemies. Amid what the Marine Corps itself has condemned as a culture of hazing and abuse at Parris Island, S.C., one of two main training depots for recruits, a widening inquiry is underway involving mistreatment that targeted brand-new Muslim Marines, one of whom wound up dead at the bottom of a barracks stairwell.

It is hard to imagine a greater propaganda gift to Islamist extremists than the incidents now under investigation at Parris Island, which can and will be portrayed as evidence of America’s cruelty and inexorable hostility to Islam. The revelations are also likely to subvert the Marines’ recruitment efforts at home, and not only among young Muslim Americans.

In one instance last year, a drill instructor is accused of badgering a Muslim recruit by calling him a terrorist and ordering him repeatedly into a spinning industrial clothes dryer, leaving him with burns on his neck and arm. In another, involving the same drill instructor, this March, a 20-year-old Muslim recruit, Raheel Siddiqui, valedictorian of his high school in Michigan, jumped 40 feet to his death down a stairwell after he was verbally abused and slapped. He had arrived at Parris Island just 11 days earlier.

The victims in these cases are young Americans who elected voluntarily to serve their country and challenge themselves by entering a military service famed for its patriotism and professionalism. In return for their service, they were hounded, persecuted and treated as pariahs. The alleged abuse violated Marine Corps policies and procedures, yet the chain of command at Parris Island seemed content to look the other way.

These were not isolated episodes involving a rogue drill instructor; as the Marines’ own assessment has shown, they were part of a pattern involving the 3rd Recruit Training Battalion at Parris Island, through which tens of thousands of young Marines pass annually.

White House press secretary Josh Earnest talked with reporters at the daily briefing about reports that a Marine drill instructor put a Muslim recruit into an industrial clothes dryer multiple times. The investigative documents have not been made public, but were reviewed by The Washington Post. (The White House)

Marine Corps investigative documents reviewed by The Post’s Dan Lamothe paint a chilling picture. Some drill instructors were drunk on the job; some repeatedly ordered unauthorized training exercises that left recruits injured. Ethnic and homophobic slurs were commonplace.

Twenty officers and senior enlisted Marines are facing administrative discipline or criminal charges; some have already been removed from command, including the colonel in charge of training at Parris Island. Given the extent and severity of the alleged misconduct, there is reason to believe the Marines must go further if they truly want to uproot the rot at Parris Island.

The Marine Corps has done itself a grave disservice. It will need more than cosmetic reforms intended to placate public opinion or congressional scrutiny. The Marines say they have taken immediate steps to enforce a “zero-tolerance” policy on hazing at Parris Island as well as at its West Coast training facility in San Diego, which has not been subject to similar allegations. That’s a good start; it now needs tough implementation and follow-up to regain the prestige it has lost.