LONDON -- NATO ally Poland scrambled "military aviation" in its airspace early Tuesday morning in response to Russian missile strikes in western Ukraine, the country's Operational Command said.

Gas supplies were also cut off in western Ukraine after a 'critical industrial facility was struck in Ternopil', local officials said. Energy firm Naftogaz confirmed its facilities were also hit.

Putin has previously said that European or U.S forces in Ukraine would be a major security issue for Russia. He has never publicly indicated that he would accept Western troops in Ukraine ...