Russia seized Ukraine's Crimea Peninsula in 2014, and pro-Russia rebels have since been fighting Ukrainian forces in the eastern areas of Donetsk and Luhansk. More than 14,000 people have been killed in the conflict.
After weeks of rising tension as Moscow massed over 150,000 troops on Ukraine's borders, Russian President Vladimir Putin on Monday recognised the two regions' independence and ordered Russian forces there as what he called "peacekeepers." U.N. Secretary-General Antonio Guterres disputed that, saying they are troops entering another country without its consent.
"Our world is facing a moment of peril," Guterres told the assembly.