Russian President Vladimir Putin has announced a military operation in Ukraine, and he is warning other countries that any attempt to interfere with the Russian action would lead to “consequences they have never seen."
US President Joe Biden says the world will “hold Russia accountable."
The Ukrainian president earlier rejected Moscow's claims that his country poses a threat to Russia and made a passionate plea for peace.
Before Putin's announcement, world leaders worked to maintain a united stance and vowed to impose tougher sanctions in the event of a full-fledged invasion.
The United Nations Security Council held an emergency meeting Wednesday night at Ukraine's request.
Here are the things to know about the conflict over Ukraine and the security crisis in Eastern Europe:
PUTIN MAKES HIS MOVE
Putin said the military operation was needed to protect civilians in eastern Ukraine — a claim the US had predicted he would falsely make to justify an invasion.
In a televised address, Putin accused the US and its allies of ignoring Russia's demand to prevent Ukraine from joining NATO and offer Moscow security guarantees. He said Russia's goal was not to occupy Ukraine.
US President Joe Biden denounced the attack as “unprovoked and unjustified.”
As Putin spoke, big explosions were heard in Kyiv, Kharkiv and other areas of Ukraine.
UKRAINE'S PRESIDENT MAKES PLEA FOR PEACE
Speaking in Russian, President Volodymyr Zelenskyy gave an emotional address early Thursday.
“The people of Ukraine and the government of Ukraine want peace,” he said. “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.”
Zelenskyy said he asked for a call with Putin late Wednesday but the Kremlin didn't respond.
Earlier Wednesday, Ukraine imposed a nationwide state of emergency, which allows authorities to impose restrictions on movement, block rallies and ban political parties and organizations.
WHAT ACTION IS THE UNITED NATIONS TAKING?
The UN Security Council held another emergency meeting on Ukraine on Wednesday night, just two days after another emergency session saw no support for Russia's decision to recognize the two rebel regions of Ukraine as independent and to order Russian troops there for “peacekeeping.”
"If indeed an operation is being prepared, I have only one thing to say from the bottom of my heart: President Putin, stop your troops from attacking Ukraine. Give peace a chance. Too many people have already died,” UN Secretary-General Antonio Guterres told the council.
Council diplomats are now finalizing a draft of a resolution that would declare that Russia is violating the UN Charter, international law and a 2015 council resolution on Ukraine, a diplomat said, speaking on condition of anonymity because the discussions were private.
The resolution would urge Russia to come back into compliance immediately, the diplomat said.
At a General Assembly meeting earlier Wednesday, Russia and ally Syria defended Moscow's moves. But even China, which usually takes Russia's side at the UN, spoke up for the world body's longstanding principle of respecting countries' sovereignty and internationally recognized borders, while not mentioning Russia by name.
WHEN WILL THE WEST IMPOSE MORE SANCTIONS?
Ukraine's forces are no match for Moscow's military might, so Kyiv is counting on other countries to hit Russia hard — with sanctions.
Ukrainian Foreign Minister Dmytro Kuleba said on Twitter that the West should target Putin where it hurts without delay. “Hit his economy and cronies. Hit more. Hit hard. Hit now,” Kuleba wrote.
Biden on Wednesday allowed sanctions to move forward against the company that built the Russia-to-Germany Nord Stream 2 gas pipeline and against the company's CEO.
Biden waived sanctions last year when the project was almost completed, in return for an agreement from Germany to take action against Russia if it used gas as a weapon or attacked Ukraine. Germany said Tuesday it was indefinitely suspending the pipeline.
Ukraine's Western supporters said they had already sent out a strong message with a first batch of sanctions on Tuesday. They said Russian troops moving beyond the separatist-held regions would produce more painful sanctions and possibly the biggest war in a generation on Europe's mainland.
“This is the toughest sanctions regime we've ever put in place against Russia,” British Foreign Secretary said of measures that target key banks that fund the Russian military and oligarchs. "But it will go further, if we see a full-scale invasion of Ukraine.”
The European Union finalized a similar package, which also targets legislators in the lower house of Russia's parliament and makes it tougher for Moscow to get on EU financial and capital markets.
US actions announced Tuesday target high-ranking Russian officials and two Russian banks considered especially close to the Kremlin and Russia's military, with more than $80 billion in assets.
HOW IS UKRAINE'S ECONOMY HOLDING UP?
It is Ukraine, not Russia, where the economy is eroding the fastest under the threat of war.
One by one, embassies and international offices in Kyiv have closed. Flight after flight was cancelled when insurance companies balked at covering planes arriving in Ukraine. Hundreds of millions of dollars in investment dried up within weeks.
The squeezing of Ukraine's economy is a key destabilizing tactic in what the government describes as “hybrid warfare” intended to eat away at the country from within.
UKRAINE SEES MORE CYBERATTACKS
Ukraine's parliament and other government and banking websites were hit with another wave of distributed-denial-of-service attacks Wednesday.
Unidentified attackers had also infected hundreds of computers with destructive malware, cybersecurity researchers said.
Officials have long said they expect cyberattacks to precede and accompany any Russian military incursion, and analysts said the incidents hew to a nearly two-decade-old Russian playbook of wedding cyber operations with real-world aggression.
HOW IS THE CONFRONTATION SEEN IN RUSSIA?
Russian state media are portraying Moscow as coming to the rescue of war-torn areas of eastern Ukraine that are tormented by Ukraine's aggression.
TV presenters are professing the end of suffering for the residents of the breakaway regions.
“You paid with your blood for these eight years of torment and anticipation,” anchor Olga Skabeyeva said during a popular political talk show Tuesday morning. “Russia will now be defending Donbas.”
WHO IS BACKING RUSSIA IN THE CRISIS?
Russia is not facing the rest of the world on its own. China is leaning toward Russia and accused the US of stoking the Ukraine crisis.
Chinese Foreign Ministry spokesperson Hua Chunying said Washington “keeps sending weapons to Ukraine, creating fear and panic and even playing up the threat of war.”
She said China has been calling on all parties to respect one another's legitimate security concerns.