Russian President Vladimir Putin has warned NATO alliance leaders that a move to lift restrictions on Ukraine’s use of longer-range Western missiles to strike deep inside his country would be considered an act of war.

The head of NATO’s military committee says that Ukraine has the solid legal and military right to strike deep inside Russia to gain combat advantage, reflecting the beliefs of a number of U.S. allies.

The Russian president said Western support for Ukrainian strikes deep inside Russia would put his country and NATO “at war.”