UN Secretary-General Antonio Guterres will start a difficult three-day trip to Russia and Ukraine on Tuesday amid criticism for the limited role played by the United Nations in the management of the crisis. Al Jazeera reports that three months into the Russian invasion of Ukraine, UN agencies are struggling to reach civilians under siege in the east of the country, where humanitarian assistance is sporadic. Meanwhile the UN Security Council, where Russia is one of five permanent members with veto power, has failed to pass any resolutions condemning the war.