World leaders condemn Russia's 'path of destruction' in pursuing an 'unprovoked' and 'unjustified' invasion of Ukraine

• World leaders are speaking out against Russia's invasion of Ukraine and Vladimir Putin.
• NATO leaders called the attack "unjustified" and "unprovoked" and vowed to respond with sanctions.

World leaders are reacting with shock and alarm to Russia's attack on Ukraine, which Ukraine's leaders have deemed a "full-scale invasion."

After months of escalating tensions and troop building, Russian President Vladimir Putin early Thursday declared a "special military operation" in Ukraine. The announcement was immediately followed by explosions and artillery blasts in multiple cities. Many Ukrainian citizens tried to flee the country in their cars and lined up to take their money out of banks. In the city of Kharkiv, people sheltered in a subway station that was turned into a makeshift bomb shelter.

Russia's war on Ukraine represents an immediate threat to the country and its citizens and could lead to a far more significant destabilization of Eastern Europe.

"Under the present circumstances, I must change my appeal: President Putin, in the name of humanity, bring your troops back to Russia. This conflict must stop now," United Nations Secretary-General António Guterres tweeted in response.

But the conflict is already in full swing.

Many countries in NATO, of which Ukraine is not a member, spoke out in condemnation of Russia's actions, expressing support for Ukraine and vowing to place strong sanctions on Russia. Ukraine's Ministry of Foreign Affairs retweeted a number of criticisms and support of Ukraine from both heads of state and foreign-affairs chiefs from around the world.

In a statement issued on Wednesday at 10:40 p.m. local time, President Joe Biden called the invasion "an unprovoked and unjustified attack by Russian military forces."

"President Putin has chosen a premeditated war that will bring a catastrophic loss of life and human suffering," Biden added. "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."

UK Prime Minister Boris Johnson tweeted that he was "appalled by the horrific events in Ukraine" and had spoken with Ukrainian President Volodymyr Zelensky "to discuss next steps."

"President Putin has chosen a path of bloodshed and destruction by launching this unprovoked attack on Ukraine," Johnson wrote. "The UK and our allies will respond decisively."

Canadian Prime Minister Justin Trudeau tweeted: "Canada condemns — in the strongest possible terms — Russia's egregious attack on Ukraine."

He added: "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 UN."

French President Emmanuel Macron, who conducted a shuttle-diplomacy effort to try to avert a full-scale war, said the attack marked "a turning point in the history of Europe."

"We will respond to this act of war without weakness, with cold blood, determination, and unity," Macron said in a Thursday address.

Biden met with G7 leaders on Thursday morning and plans to announce new sanctions on Russia later in the day.

NATO Secretary-General Jens Stoltenberg put the stakes starkly on Wednesday night, calling the attack "a brutal act of war."

"We now have war in Europe on a scale and of a type we thought was left to history," he said.

Former US President George W. Bush also spoke out, calling the Russian attack "the gravest security crisis on the European continent since World War II" and saying Putin's actions were "unprovoked and unjustified."

Russia's conflict with Ukraine escalated dramatically in recent weeks. The Kremlin assembled vast numbers of troops around Ukraine — as many as 190,000, according to US estimates — in the largest military operation in the region since World War II.

On Monday, Putin recognized the claims to independence of the breakaway Luhansk and Donetsk areas of Ukraine, ordering troops there for what he described as a limited peacekeeping operation.

Less than 72 hours later, Putin authorized a full-scale attack on Ukraine. In the hours that followed, explosions pounded cities around Ukraine. Ukrainian officials reported fighting on its borders with Russia and dozens of casualties.

The new wave of hostilities expanded the clash from a limited incursion over disputed land into the most serious armed conflict in Europe for at least a decade. Insider's live blog of the invasion is covering developments as they happen.