UN forces in Somalia are the latest peacekeeping operation to be hit with accusations that the troops have been abusing the local women. Such misbehavior is nothing new, but once the Cold War ended in 1991 and the old superpower rivalries were gone, it was a lot easier for the UN to organize peacekeeping operations. Now there were a lot more peacekeepers in action and the usual dynamic of men with guns and women without much of anything continued. By the end of the 1990s the media was beginning to notice and since then all manner of misbehavior by peacekeepers has been noted and publicized.
With that there was more pressure on the UN to end, or at least regulate, the practice. Since most of the peacekeeping operations have been in Africa that’s where most of the incidents of misbehavior have been noted. The latest complaints come from Somalia but in 2013 the UN was called on to investigate charges that some of its Mali peacekeepers were guilty of corruption and “sexual misconduct” (which apparently includes rape, prostitution, or other mistreatment of women). Before that it was Ivory Coast, where Moroccan peacekeepers were accused of having sex with local teenage girls. In fact, just about every peacekeeping operation in Africa, and most of those elsewhere, have been found to be tainted by some sort of bad behavior.
After 2001 the accusations piled up and the old ways of handling the complaints no longer sufficed. For a long time the UN did not bother with the sexual activity of peacekeepers unless it involved rape or murder. Even then, someone, preferably an aid worker (NGO or UN) had to make the complaint. If was quickly discovered that complaints got a lot more attention, and more quickly, if they were made to Western media, preferably British. The British media has a thing for sexual abuse in far off lands.
The UN would like the entire matter to go away. There has always been a shortage of peacekeepers and broadcasting the fact that sexual activity will be monitored by civilian aid workers and foreign journalists does little to encourage troops to volunteer. Then again, the most severe punishment usually handed out is to send specific soldiers home. They lose their extra pay for being a peacekeeper, and might suffer career damage if they were professional soldiers. This is meaningful for many peacekeepers, whose regular pay is, at most, a few hundred dollars a month. The UN pays the contributing nation $1,000 a month (or more) per soldier, but the troops don't always get all of that.
The peacekeepers, especially the ones from poor countries, did not see the point in a lot of this criticism. For example the peacekeepers from poor countries were familiar with what the locals were going through and often were trading food for sex. This was seen, by the locals, as "survival sex" for the girls in question and the peacekeepers considered it a form of charity.
The foreigner aid workers and journalists often have sex with local women, but more frequently they do so with each other. That's safer, given all the AIDS, and other sexually transmitted diseases going around. But the peacekeeper units tend to be all-male, and generally from countries where homosexuality is not tolerated.
The current drill is for the UN to send an investigation team to the site of the allegations, write up a fairly accurate report, send a few soldiers home, and try to explain to the local aid workers, or other foreigners who are offended by peacekeeper behavior, that they ought to cut the troops some slack. This last bit is done very discretely, lest yet another sex scandal erupt.
There are often more serious situations, like peacekeepers establishing and running brothels and using their position of authority to force women to work there. Cases of rape and murder, especially if well publicized, are also more likely to result in prosecution. Amidst all this there are less newsworthy but even more damaging (to the peacekeeping effort) crimes involving corruption. This covers a wide variety of misbehavior, including theft, taking bribes and sometimes cooperating (for a large fee) with the enemy (the bad guys the peacekeepers were brought in to control.)