Peacekeeping forces often lumber along for years without clear goals or exit plans, crowding out governments, diverting attention from deeper socioeconomic problems and costing billions of dollars. My first peacekeeping mission was in Cambodia in 1992. We left after less than two years. Now it’s a rare exception when a mission lasts fewer than 10.

Look at Haiti: There has been no armed conflict for more than a decade, and yet a United Nations force of more than 4,500 remains. Meanwhile, we are failing at what should be our most important task: assisting in the creation of stable, democratic institutions. Elections have been postponed amid allegations of fraud, and the interim prime minister has said that “the country is facing serious social and economic difficulties.” The military deployment makes no contribution at all to solving these problems.

Our most grievous blunder is in Mali. In early 2013, the United Nations decided to send 10,000 soldiers and police officers to Mali in response to a terrorist takeover of parts of the north. Inexplicably, we sent a force that was unprepared for counterterrorism and explicitly told not to engage in it. More than 80 percent of the force’s resources are spent on logistics and self-protection. Already 56 people in the United Nations contingent have been killed, and more are certain to die. The United Nations in Mali is day by day marching deeper into its first quagmire.

BUT the thing that has upset me most is what the United Nations has done in the Central African Republic.When we took over peacekeeping responsibilities from the African Union there in 2014, we had the choice of which troops to accept. Without appropriate debate, and for cynical political reasons, a decision was made to include soldiers from the Democratic Republic of Congo and from the Republic of Congo, despite reports of serious human rights violations by these soldiers. Since then, troops from these countries have engaged in a persistent pattern of rape and abuse of the people — often young girls — the United Nations was sent there to protect.

Last year, peacekeepers from the Republic of Congo arrested a group of civilians, with no legal basis whatsoever, and beat them so badly that one died in custody and the other shortly after in a hospital. In response there was hardly a murmur, and certainly no outrage, from the responsible officials in New York.

As the abuse cases piled up, impassioned pleas were made to send the troops home. These were ignored, and more cases of child rape came to light. Last month, we finally kicked out the Democratic Republic of Congo soldiers, but the ones from the Republic of Congo remain.

In 1988, my first job with the United Nations was as a human rights officer in Cambodian refugee camps along the Thai-Cambodian border, investigating rapes and murders of the poor and helpless. Never could I have imagined that I would one day have to deal with members of my own organization committing the same crimes or, worse, senior officials tolerating them for reasons of cynical expediency.