World leaders denounce Russia's "hideous and barbaric" attacks on Ukraine

What they're saying:

President Biden

• "Russia alone is responsible for the death and destruction this attack will bring, and the United States and its allies and partners will respond in a united and decisive way. The world will hold Russia accountable," Biden said in a statement shortly after the attacks began.

Boris Johnson

• "Our worst fears have now come true and all our warnings have proved tragically accurate. President Putin of Russia has unleashed war in our European continent. He's attacked a friendly country without any provocation and without any credible excuse," British Prime Minister Boris Johnson said.
• "Ukraine is a country that for decades has enjoyed freedom and democracy and the right to choose its own destiny," he added. "We and the world cannot allow that freedom just to be snuffed out. We cannot and will not just look away."
• The prime minister announced a "massive package of economic sanctions designed in time to hobble the Russian economy."
• "Our mission is clear: diplomatically, politically, economically and eventually militarily, this hideous and barbaric venture of Vladimir Putin must end in failure."

Emmanuel Macron

• "The events of this night are a turning point in the history of Europe and our country," said France's Emmanuel Macron in a speech early Thursday, adding that "to this act of war, we will respond without weakness."

• "Putin rejected the diplomatic path and chose the path of war. We will take full responsibility for defending the sovereignty of our allies."
• Like other world leaders, Macron announced sanctions on Russia, saying that they "will be commensurate with the actions of which it is guilty."

Olaf Scholz

• "This 24th of February is a terrible day for Ukraine and a very dark day for Europe,” German Chancellor Olaf Scholz said.
• “In attacking Ukraine, President Putin is blatantly infringing on international law.”
• After announcing “severe” sanctions against Russia, Scholz said that their “aim” is to let Putin know that the Russian regime “will pay a bitter price for this aggression. It will be clear to Putin that he has made a terrible mistake by unleashing this war.”

Justin Trudeau

• "These unprovoked actions are a clear further violation of Ukraine’s sovereignty and territorial integrity, and of Russia’s obligations under international law and the Charter of the U.N.," said Canadian Prime Minister Justin Trudeau.
• "Canada calls on Russia to immediately cease all hostile and provocative actions against Ukraine, and withdraw all military and proxy forces from the country. Ukraine’s sovereignty and territorial integrity must be respected."

Dmytro Kuleba

• "Ukraine has severed diplomatic relations with Russia. I call on all our partners to do the same," said Ukrainian Foreign Minister Dmytro Kuleba.
• "By this concrete step, you will demonstrate that you stand by Ukraine and categorically reject the most blatant act of aggression in Europe since WWII."
• "Right now, Putin is plunging Europe into its darkest time since 1939. Any government hoping to sit this out is naïve. Don’t repeat mistakes of the past. Hit Russia with severe sanctions now. Help Ukraine with military and financial support," Kuleba said.

António Guterres

• "President Putin, in the name of humanity, bring your troops back to Russia," United Nations Secretary-General António Guterres tweeted on Thursday. "This conflict must stop now."
• "Our world is facing a moment of peril. I truly hoped it would not come. The latest developments regarding Ukraine are a cause of grave concern," Guterres said in a speech to the UN General Assembly on Wednesday evening.
• "As we sadly know all too well, in conflict, civilians, including women and children, always suffer first and suffer most. If the conflict in Ukraine expands, the world could see a scale and severity of need unseen for many years," he added.

Jens Stoltenberg

• "Peace on our continent has been shattered," NATO Secretary-General Jens Stoltenberg said at an emergency press conference Thursday.

• "We now have war in Europe on a scale and of a type we thought belonged to history."
• "This is a deliberate, cold-blooded and long-planned invasion."
• "The Kremlin's aim is to re-establish its sphere of influence, rip up the global rules which have kept us all safe for decades and subvert the values that we hold dear. This is the new normal for our security. Peace cannot be taken for granted," Stoltenberg said.

Ursula von der Leyen

• "Once again, in the center of Europe, innocent women, men and children are dying or fear for their lives. We condemn this barbaric attack, and the cynical arguments to justify it," European Commission President Ursula von der Leyen said in a statement.
• "It is President Putin, who is bringing war back to Europe. In these dark hours, the European Union and its people stand by Ukraine and its people. We are facing an unprecedented act of aggression by the Russian leadership against a sovereign, independent country," she added.
• "Russia's target is not only Donbas, the target is not only Ukraine, the target is the stability in Europe and the whole of the international peace order. And we will hold President Putin accountable for that."
• "We will not let President Putin tear down the security architecture that has given Europe peace and stability over many decades. We will not allow President Putin to replace the rule of law by the rule of force and ruthlessness. He should not underestimate the resolve and strength of our democracies."

Filippo Grandi

• "We are gravely concerned about the fast-deteriorating situation and ongoing military action in Ukraine," said U.N. High Commissioner for Refugees Filippo Grandi. "The humanitarian consequences on civilian populations will be devastating. There are no winners in war, but countless lives will be torn apart."
• "UNHCR is working with the authorities, U.N. and other partners in Ukraine and is ready to provide humanitarian assistance wherever necessary and possible. To that effect, security and access for humanitarian efforts must be guaranteed."

What we're watching: G7 leaders will meet on Thursday morning to discuss the ongoing Russian attack. More statements are expected later in the day.

Go deeper: Ukraine-Russia crisis latest developments

Editor's note: This story will be updated as more statements are made.