Estonian PM: NATO must stop 'war criminal' Putin

NATO should "double" its efforts to end Russia's war in Ukraine, Estonian Prime Minister Kaja Kallas has said at the start of an extraordinary summit of the defence alliance in Brussels.

"I think we have to double our efforts - Putin cannot win this war," Kallas said, referring to Russian President Vladimir Putin, whose war in Ukraine started exactly one month ago.

The Kremlin leader is taking steps "to make us afraid" and "deter us from helping Ukraine further or making additional steps."

"We should definitely not fall into that trap - we have to stop the war criminal," she said.