Prime Minister Stephen Harper's official Twitter account says the flag, which is on display just east of the Centre Block, illustrates Canada's solidarity with the Ukrainian people.
Russian President Vladimir Putin, meanwhile, spoke out today to assert his country's right to use its military to protect Russians in Ukraine.
Putin also says any sanctions against Russia by the United States and the European Union will backfire.
He accused the West of sowing divisions within Ukraine.
— With files from The Associated Press
Also on HuffPost