Incident has sparked concerns that U.S. and Russia could be brought closer to direct conflict
Ukraine has invited Florida Governor Ron DeSantis to visit after he said the Russian invasion was a "territorial dispute" with Russia which was not one of the US's "vital national interests".
But details beyond that remain sketchy.
Ukrainian President Volodymyr Zelensky has said he plans to meet China's leader Xi Jinping to discuss Beijing's proposals on ending the war in Ukraine.
Moldova's leaders have rejected Russian claims that Ukraine is planning to attack the country's breakaway pro-Russian territory, and called for calm.
The US has marked a year since Russia invaded Ukraine by announcing a new range of sanctions against Russia and new military aid for Ukraine.
