United Nations peacekeepers in Congo sexually exploited women and girls, some as young as 13, a U.N. watchdog office said Friday in a new confirmation that efforts to curb abuses by U.N. troops are not working. Charges of sex abuse and other crimes have been lodged against U.N. peacekeeping missions around the world for decades. Officials have found it difficult to crack down because the United Nations doesn't want to offend the relatively small number of countries that are willing to provide peacekeepers.