Ukrainian President Petro Poroshenko has said that Russia's aggressive actions have proved the necessity of and lack of alternatives to NATO's expansion.

"No one else but Russia with its aggressive actions convincingly proved the usefulness of the organization, the need for its reinforcement and further expansion. There's no alternative," he said at an extending meeting of the National Defense and Security Council of Ukraine in Kyiv on Tuesday.

Poroshenko said that NATO was the only international organization that had reacted to Russian threats to regional and international security.

He went on to thank NATO Secretary General Jens Stoltenberg, who was present at the meeting, for NATO's offer of help to Ukraine.