The UN is warning of a potential humanitarian catastrophe in Sudan, with reports of possible atrocities and violence against civilians. The situation is described as particularly dire in cities such as al-Obeid and el-Obeid, with concerns about famine, drone strikes, and blocked aid. The UN has issued warnings and taken steps, including adopting a fact-finding mission, to address the crisis, which may be linked to rebel activity and has drawn condemnation from countries like the UK.