A disturbing internal report from the United Nations says its own peacekeepers may have been responsible for dozens of cases of sexual assault and exploitation in Haiti, including many cases involving children.

According to a review of that report by the Associated Press, at least 134 peacekeepers from Sri Lanka who took part in the U.N.’s political stabilization mission in Haiti allegedly ran a sex ring involving children from 2004 to 2007. All but about 20 of the peacekeepers were sent home — but none went to jail.

It's not the first time U.N. personnel have been accused of such crimes.

The AP noted that U.N. investigators uncovered many more allegations against peacekeepers and U.N. staff across the globe over the past 12 years, including at least 300 cases of sex crimes against children. However, few of the suspected perpetrators have been prosecuted. 

The U.N. technically can’t press charges against personnel accused of such crimes. Instead, they must be prosecuted by their respective home countries — though even then many cases do not result in jail time. 

A 2011 case involved three Pakistani peacekeepers accused of raping a mentally-challenged 13 year-old boy in Haiti; the boy was abducted to prevent him from testifying. The peacekeepers were eventually sent back to Pakistan to face charges, but U.N. observers were not allowed to witness the proceedings. The only soldier who was sentenced spent a year behind bars.

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Haiti has been wracked by political unrest over the years and has struggled to rebuild from a devastating earthquake in 2010 — and a subsequent and deadly cholera outbreak linked to U.N. personnel. Haitian victims cited in the report frequently told investigators they were coerced into performing sexual acts with the promise of food or money.

In 2015, the head of the U.N. mission in the Central African Republic was forced to resign following reports that French peacekeepers there sexually assaulted civilians and children; no charges were filed in that case, either. 

Just last month, U.N. Secretary-General António Guterres unveiled a proposal to vet new peacekeepers in a way that would screen out potential sex offenders. The hope is it's more effective than previous attempts to reform that, according to an analysis from Cornell University Law School, have all failed to address the problem.

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The outcry over that scandal reached the U.S. Capitol last year,when Senate Foreign Relations Committee Chairman Bob Corker threatened to pull back U.S. funding for the U.N. unless it did more to address the problem.

The Trump administration has indicated that it wants to slash its contribution to the U.N. by as much as $1 billion, which would also undercut peacekeeping missions around the world.

The U.N., meanwhile, is set to vote Thursday on scaling back its 13 year peacekeeping mission in Haiti.