The massing of 100,000 Russian troops on Ukraine’s border has prompted fears of an invasion — and global leaders are scrambling to reduce tensions. We discuss what could happen, and Canada’s role, with Illia Ponomarenko, defence reporter with the Kyiv Independent; Aurel Braun, a professor of international relations and political science at the University of Toronto; and Constanze Stelzenmüller, the Fritz Stern Chair on Germany and trans-Atlantic Relations at the Brookings Institution.