By Jessie Yeung, Adam Renton, Rob Picheta, Ed Upright, Aditi Sangal, Adrienne Vogt, Melissa Macaya and Maureen Chowdhury, CNN
From CNN’s Tim Lister and Ingrid Formanek in Kyiv
CNN teams in the Ukrainian capital Kyiv are hearing explosions come from the east, in the direction of the international airport.
Reports on social media indicate several explosions in the Boryspil area to the east of the capital, where the international airport is located.
Two people in the Ukrainian city Kramatorsk also told CNN they have heard at least two massive explosions in the early hours of Thursday.
In a statement early Thursday morning, US President Joe Biden condemned Russia's actions, shortly after Russian President Vladimir Putin announced military action in the Donbas region of eastern Ukraine.
Biden's statement:
“The prayers of the entire world are with the people of Ukraine tonight as they suffer 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. 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 added that he is monitoring the situation from the White House, and will meet with the other G7 leaders in the morning. He will announce "further consequences" imposed on Russia by the US and its allies tomorrow, he said.
In an early morning address on national television, Russian President Vladimir Putin said: “Our plans are not to occupy Ukraine, we do not plan to impose ourselves on anyone."
Early Thursday morning, Putin said his troops will take military action in Donbas, the area of eastern Ukraine that contains the separatist-held regions of Donetsk and Luhansk which he recognized as independent on Monday.
The CNN team in Kharkiv, the second-largest city in Ukraine located in the country's northeast, is hearing a "steady stream of loud explosions."
CNN reporters on the ground also reported hearing explosions near the capital Kyiv.
From CNN's Nathan Hodge in Moscow
In an address early Thursday on national television, Russian President Vladimir Putin announced military action in Donbas, urging Ukrainian forces to lay down their arms and go home, according to state-run news agencies RIA-Novosti and TASS.
Putin warned that all responsibility for any potential bloodshed will be on the conscience of the Ukrainian government, and said he was confident Russian service members will fulfill their duty.
The CNN team on the ground is hearing several loud explosions near Kyiv, the capital of Ukraine.
Watch Matthew Chance reporting:
From CNN’s Oren Liebermann and Tim Lister
Ukraine's aviation authorities have issued a notice restricting the country's airspace starting early Thursday morning and lasting until midnight GMT (7 p.m. ET).
The alert, known as a Notice to Airmen (NOTAM), covers all five of the country's flight information regions (FIRS) — restricting aviation in the regions around around Kyiv, Dnipro, Lviv, Odessa and Simferopol.
The flight tracking service FlightRadar24 shows a flight from Warsaw to Kyiv, Lot 755, turned around before entering Ukrainian airspace and is returning to the Polish capital.
The website shows no civil aircraft in Ukrainian airspace.
From CNN's Nathan Hodge in Moscow
Russian President Vladimir Putin says his troops will take action in the separatist-held region of Ukraine he declared independent this week.
From CNN’s Mirna Alsharif
United Nations Secretary General Antonio Guterres told Russian President Vladimir Putin to stop "attacking Ukraine" and to give peace a chance, speaking at an emergency UN Security Council meeting on Wednesday night.
“The day was full of rumors and indications of an offensive against Ukraine was imminent. In the recent past, there were several situations with similar indications, similar rumors. And I never believed in them, convinced that nothing serious would happen,” Guterres told the council. “I was wrong. And I would like not to be wrong again today.”
“So, if indeed an operation is being prepared, I've only one thing to say from the bottom of my heart: President Putin, stop your troops from attacking the Ukraine. Give peace a chance. Too many people have already died."
