EU chief Ursula von der Leyen said the European Union will hold Russia "accountable" for its military operation in Donbass.

She further said that the Union is preparing more sanctions that will deal "massive and severe consequences" to Russia.

"We strongly condemn Russia's unjustified attack on Ukraine," European Commission President Ursula von der Leyen wrote on Twitter.

We condemn Russia’s unprecedented military aggression against Ukraine.

It must withdraw its military and fully respect Ukraine's territorial integrity.

The EU leaders will discuss and swiftly adopt further restrictive measures against Russia.

The EU stands with Ukraine.

— Ursula von der Leyen (@vonderleyen) February 24, 2022

The statement further said that their thoughts are with "Ukraine and the innocent women, men and children as they face this unprovoked attack and fear for their lives."

Russia's Defense Ministry said on Thursday that Moscow's Armed Forces are not attacking Ukrainian cities, but are instead targeting Ukraine's military infrastructure using precision weapons.

"Precision weapons are degrading military infrastructure, air defense facilities, military aerodromes and aviation of the Ukrainian armed forces," the ministry said, further adding that there is no threat to civilians.

The European bloc will hold a snap summit late Thursday, which will discuss the Ukraine crisis and "further restrictive measures" aimed against Russia.

"We are coordinating our response with our international partners, including NATO and G7 whose leaders will meet today (Thursday)," von der Leyen said.

Europe is united in its impactful response to Russia's illegal actions and threats to Ukraine and its people.

We welcome the swift adoption of the sanctions package by the Council.

We stand for a rules based international order.

— Ursula von der Leyen (@vonderleyen) February 23, 2022

NATO chief: Russia has chosen the path of aggression

NATO Secretary-General Jens Stoltenberg denounced Russia's "reckless and unprovoked" military operation in Donbass, saying it will put "countless" lives in jeopardy.

NATO has been ramping up its military presence in Eastern Europe for months, conducting military exercises on Russia's borders, and sending lethal weapons to Ukraine. 

"Once again, despite our repeated warnings and tireless efforts to engage in diplomacy, Russia has chosen the path of aggression against a sovereign and independent country," Stoltenberg said in a statement. 

The NATO chief further called the military operation a "grave breach of international law, and a serious threat to Euro-Atlantic security."

Macron, Draghi condemn Russian military operation

French President Emmanuel Macron condemned the Russian military operation in support of the Donbass republics, and said Paris would work with its allies to "end the war".

"Russia must immediately put an end to its military operations," Macron wrote on Twitter, saying Russia had made the decision to "wage war" on Ukraine.

La France condamne fermement la décision de la Russie de faire la guerre à l’Ukraine. La Russie doit mettre immédiatement fin à ses opérations militaires.

— Emmanuel Macron (@EmmanuelMacron) February 24, 2022

Italian Prime Minister Mario Draghi also condemned Russia's move, calling it "unjustified and unjustifiable", and said that EU and NATO were working on an immediate response.

"The Italian Government condemns Russia's attack on Ukraine. It is unjustified and unjustifiable. Italy is close to the Ukrainian people and institutions in this dramatic moment. We are working with European and NATO allies to respond immediately, with unity and determination," Draghi said in a statement.