The WMD's were never confirmed by UN but in this case, UN is saying they have found witness accounts of massive sexual violence. Also, the number of young girls of 13 - 20 are disproportionately low compared to the population of refugees.
This correlates with the witness accounts and reports that Burmese soldiers have raped and killed young girls in a massive scale.
RE: Politics: Some insight into the Rohingya & Myanmar conflict