The U.S. military's response to suspected child sexual abuse in Afghanistan is the subject of a new research project by the Pentagon's top watchdog.

The Defense Department Inspector General's Office on Tuesday announced a new probe that will look at how U.S. troops handled repeated allegations that Afghan men, particularly Afghan military and police leaders, were sexually abusing boys.

A number of American troops who deployed to Afghanistan have said they saw signs of widespread sexual abuse and believed there was a policy, even if unofficial, encouraging them to ignore the crime rather than create tension between Americans and Afghans.

The sexual abuse of boys is widespread in Afghanistan, often referred to as "Bacha Bazi" — literally, "boy play."

The IG said the probe is a "research" project, meaning it is not a full-blown investigation. The research effort will include interviews with officials inside and outside the military along with an analysis of relevant laws and policies. After that review, the IG will determine whether to pursue an investigation, which could result in policy changes or disciplinary actions.

For now, the IG will confine its review to the period since 2011. Investigators will examine whether the U.S. military maintained any formal or informal rules or policies discouraging American troops from reporting suspected sexual abuse by Afghans.

The inquiry also will look at what international laws or treaties might govern the U.S. handling of the allegations, according to an IG memo released Tuesday.

The IG wants to know how many cases of child sexual abuse were reported to U.S military commands, how those reports were handled and how many were relayed to Afghan authorities, according to the memo from Kenneth Moorefield, deputy inspector general for special plans and operations.

The top U.S. commander in Afghanistan, Army Gen. John Campbell, faced questions on this issue Oct. 6 when he testified on Capitol Hill.

Campbell said he was unaware of any U.S. troops lodging reports of sexual abuse by Afghan security personnel during his tenure, which began last year. "And I think that is a result of the Afghans' understanding that they have to get after this," he said.

Several troops have said they were punished or disciplined for intervening or taking action against Afghans whom they believed were sexually assaulting children, in some cases on joint military installations. Several specific examples were reported Sept. 19 by The New York Times.

Campbell said those allegations, which are being handled internally by the Army and Marine Corps, predate his command. "I didn't have anything to do with those cases," he said in response to a question. "The cases that you refer to are four, five, six years ago. I can't speak to those."

But he said he does not believe that U.S. service members have ignored evidence of child sexual assault. "This is ... a fundamental value of our military, to treat people with dignity and respect."

Congress has voiced concern on the matter. "This committee treats such allegations with the utmost seriousness," Senate Armed Services Committee Chairman Sen. John McCain, R-Ariz., told Campbell.

"It is precisely because we're fighting for progress and fighting for our values that it's been so disturbing to read reports alleging that some of our coalition partners may be engaged in sexual abuse and other activities that contradict our values," McCain said Tuesday.