The U.N. peacekeeping mission in Haiti will end in a few months, but not before reckoning with a fresh scandal.

A U.N. battalion of Nepalese peacekeepers in 2010 introduced a lethal strain of cholera to Haiti, where it has since killed over 9,000 people and infected hundreds of thousands. Now, The Associated Press reports that at least 134 U.N. peacekeepers from Sri Lanka took part in a sex ring in Haiti that victimized nine children from 2004 to 2007. The report should serve notice that U.N. peacekeeping operations worldwide are badly in need of reform and oversight.

The sex ring was part of what appears to have been a broader pattern of sexual exploitation and abuse, along with impunity, that has marked the U.N. mission in Haiti since it began in 2004 after an elected president was overthrown. The AP turned up hundreds of allegations of abuse in Haiti, carried out by peacekeepers from Bangladesh, Brazil, Jordan, Nigeria, Pakistan, Uruguay and Sri Lanka. In very few cases did the troops face discipline.

The U.N. announcement last week that the mission in Haiti would be wound down over the coming six months was unrelated to the AP’s nearly simultaneous revelations of sex abuse by peacekeepers. The troops’ withdrawal reflects both the country’s progress toward stabilization after successful elections and financial pressure to trim peacekeeping operations.

Haiti is by no means the only place peacekeepers have treated as a sexual playground. The United Nations must insist, as a precondition for accepting peacekeeping troops, that contributing countries will court-martial and punish soldiers who commit abuse. It should also sever payments to peacekeeping contingents implicated in sexual abuse if they fail to impose discipline. In the absence of such accountability, peacekeeping missions may do more harm than good.