As Russian troops launched their attack on Ukraine on Thursday, Russian President Vladimir Putin said the “special military operation” would seek the “denazification” of its sovereign neighbor.

“Its goal is to protect people who have been subjected to bullying and genocide… for the last eight years. And for this we will strive for the demilitarization and denazification of Ukraine,” Putin said during an address on state television.

Ukraine’s President Volodymyr Zelensky is Jewish. It was not clear what exactly the Russian leader was referring to in his claims of Nazism. Russian media has repeatedly sought to portray Ukraine as being aligned with Nazism, without evidence to support such accusations.

Meanwhile, Ukraine’s official Twitter account shared a caricature of Putin being groomed by Nazi dictator Adolf Hitler, apparently implying the Russian leader had similar dreams of domination.

In his speech, Putin cast aside international condemnation and sanctions, warning other countries that any attempt to interfere would lead to “consequences you have never seen.”

Big explosions were heard before dawn in Kyiv, Kharkiv and Odessa as world leaders decried the start of a Russian invasion that could cause massive casualties and topple Ukraine’s democratically elected government.

Ukraine’s Zelensky introduced martial law, saying Russia had targeted Ukraine’s military infrastructure. Zelensky said he had talked to US President Joe Biden and the US was rallying international support for Ukraine.

Biden pledged new sanctions meant to punish Russia for an act of aggression that the international community had for weeks anticipated but could not prevent through diplomacy.

Putin justified it all in a televised address, asserting the attack was needed to protect civilians in eastern Ukraine — a false claim the US had predicted he would make as a pretext for an invasion. He accused the US and its allies of ignoring Russia’s demand to prevent Ukraine from joining NATO and offer Moscow security guarantees, and claimed that Russia doesn’t intend to occupy Ukraine but will move to “demilitarize” it and bring those who committed crimes to justice.

Biden in a written statement condemned the “unprovoked and unjustified attack” on Ukraine and he promised the US and its allies “will hold Russia accountable.” Biden said he planned to speak to Americans on Thursday after a meeting of the Group of Seven leaders. More sanctions against Russia were expected to be announced Thursday.

Ukraine’s Foreign Minister Dmytro Kuleba described the action as a “full-scale invasion of Ukraine” and a “war of aggression,” adding, “Ukraine will defend itself and will win. The world can and must stop Putin. The time to act is now.”

The Russian military said it has struck Ukrainian air bases and other military assets and hasn’t targeted populated areas. The Russian Defense Ministry statement said the military is using precision weapons to target Ukrainian air bases, air defense assets and other military infrastructure. It claimed that “there is no threat to civilian population.”

Anton Gerashchenko, an adviser to Ukraine’s interior minister, said on Facebook that the Russian military had launched missile strikes on Ukrainian military command facilities, air bases and military depots in Kyiv, Kharkiv and Dnipro.

Russian President Vladimir Putin attends a wreath-laying ceremony at the Tomb of the Unknown Soldier, near the Kremlin Wall during the national celebrations of the ‘Defender of the Fatherland Day’ in Moscow, Russia, on February 23, 2022. (Alexei Nikolsky, Kremlin Pool Photo via AP)

After the initial explosions in Kyiv, people could be heard shouting in the streets. But then a sense of normality returned, with cars circulating and people walking in the streets as a pre-dawn commute appeared to be starting in relative calm.

Beyond casualties that could overwhelm Ukraine’s government, the consequences of the conflict and resulting sanctions levied on Russia could reverberate throughout the world, affecting energy supplies in Europe, jolting global financial markets and threatening the post-Cold War balance on the continent.

Asian stock markets plunged and oil prices surged after the military action got underway. Earlier, Wall Street’s benchmark S&P 500 index fell 1.8% to an eight-month low after the Kremlin said rebels in eastern Ukraine asked for military assistance

Anticipating international condemnation and countermeasures, Putin issued a stark warning to other countries not to meddle, saying, “whoever tries to impede us, let alone create threats for our country and its people, must know that the Russian response will be immediate and lead to the consequences you have never seen in history.”

Putin urged Ukrainian servicemen to “immediately put down arms and go home.”

A Ukrainian soldier talks with her comrades sitting in a shelter at the line of separation between Ukraine-held territory and rebel-held territory near Svitlodarsk, eastern Ukraine, on Wednesday, February 23, 2022. (AP Photo/Evgeniy Maloletka)

In a stark reminder of Russia’s nuclear power, Putin warned that “no one should have any doubts that a direct attack on our country will lead to the destruction and horrible consequences for any potential aggressor.” He emphasized that Russia is “one of the most potent nuclear powers and also has a certain edge in a range of state-of-the-art weapons.”

Putin announced the military operation after the Kremlin said rebels in eastern Ukraine asked Russia for military assistance to help fend off Ukrainian “aggression,” an announcement that the White House said was a “false flag” operation by Moscow to offer up a pretext for an invasion.

Putin’s announcement came just hours after the Ukrainian president rejected Moscow’s claims that his country poses a threat to Russia and made a passionate, last-minute plea for peace.

“The people of Ukraine and the government of Ukraine want peace,” Zelensky said in an emotional overnight address, speaking in Russian in a direct appeal to Russian citizens. “But if we come under attack, if we face an attempt to take away our country, our freedom, our lives and lives of our children, we will defend ourselves. When you attack us, you will see our faces, not our backs.”

Zelensky said he asked to arrange a call with Putin late Wednesday, but the Kremlin did not respond.

Ukrainian President Volodymyr Zelensky during a joint news conference with Estonian President Alar Karis, following their talks in Kyiv, Ukraine, on February 22, 2022. (Ukrainian Presidential Press Office via AP)

In an apparent reference to Putin’s move to authorize the deployment of the Russian military to “maintain peace” in eastern Ukraine, Zelensky warned that “this step could mark the start of a big war on the European continent.”

“Any provocation, any spark could trigger a blaze that will destroy everything,” he said.