Last month, the United Nations published a damning independent investigation that said poor enforcement of policies in place to deter and report abuse meant that “the credibility of the U.N. and peacekeeping operations are in jeopardy.” Experts and officials say systemic problems still hinder the investigation and prosecution of alleged abusers, leading to the perception of impunity within U.N. ranks.

The abuse “undermines everything we stand for,” said Anthony Banbury, the U.N. assistant secretary-general for field support.

The mission in the Central African Republic, where U.N. troops and civilians were sent in 2014 to help end a civil war and support a fledgling government, stands out for its record of sexual abuse and exploitation.

“They are preying on the people they’ve come to protect,” said Parfait Onanga-Anyanga, the top U.N. official in the country.