Amid Russian "military operations" in Ukraine, NATO chief Jens Stoltenberg has convened a meeting of NATO ambassadors today to discuss the consequences of the attack.


The meeting will "address the situation in Ukraine and the consequences of Russia's unprovoked attack," said the NATO chief.


Earlier today, Stoltenberg condemned Russian President Vladimir Putin's decision of military aggression in Ukraine.  


"Despite our repeated warnings and tireless efforts to engage in diplomacy, Russia has chosen the path of aggression," Stoltenberg was quoted as saying by news agency Associated Press (AP).


Stoltenberg also warned Russia that the NATO will take all necessary steps in order to protect its allies. Calling on Moscow to immediately stop military actions in Ukraine, the NATO chief said as quoted by AP, "The invasion is a grave breach of international law, and a serious threat to Euro-Atlantic security. I call on Russia to cease its military action immediately." 


Earlier today, Russia claimed to destroy Ukrainian airbases and air defences at several places including Kharkiv and Ivano-Frankivsk in western Ukraine


"The military infrastructure of Ukrainian military air bases has been put out of action," said the Russian Defence Ministry in a statement.


In retaliation Ukraine also shot down five Russian planes and a Russian helicopter in the Luhansk region bordering Russia, reported news agency Reuters.


However, the Russian Defence Ministry denied the claims made by Ukraine.


Putin on Thursday announced 'military operation' in Ukraine to defend separatists in the eastern part of the country. "I have made the decision of a military operation," declared Putin in an address to the nation.


The Russian president also threatened retaliation against anybody challenging Russia's military action in Ukraine.


"Anyone who tries to interfere with us, or even more so, to create threats for our country and our people, must know that Russia’s response will be immediate and will lead you to such consequences as you have never before experienced in your history," Putin said in the televised address.