CNN- President Vladimir Putin of Russia announced a military action in eastern Ukraine's Donbas region early Thursday local time.

Putin encouraged Ukrainian forces to lay down their arms and return home in the message, stating that all responsibility for possible violence will fall fully on the conscience of the Ukrainian government.

"However, our intention is not to conquer Ukraine; we have no intention of imposing ourselves on anyone," he stressed.

Putin's remarks came as fears of a full-scale Russian invasion grew. The Donbas region includes the separatist-held territories of Donetsk and Luhansk, which were recognized as separate by Putin on Monday.

Before the military operation was announced, Ukrainian President Volodymyr Zelensky appealed for peace but pledged that his country would protect itself.

Following Putin's talk, US Vice President Joe Biden stated that Russia had launched a "unprovoked and unjustified attack" on the Ukrainian people.

"President Putin has deliberately selected a war that would result in a terrible loss of lives and human suffering," he stated. "Russia is solely responsible for the death and destruction caused by this attack, and the US, its Allies, and partners will respond in a united and decisive manner. The international community will hold Russia accountable."

CNN teams on the ground in Russia and Ukraine heard explosions in numerous locations of Ukraine following the declaration, including in the capital Kyiv and the city of Odessa.

A team in Kyiv's capital reported hearing explosions coming from the direction of the international airport, around 15 miles (24 kilometers) east of the city. Several explosions were reported on social media in the Boryspil district to the east of the capital, which is home to the international airport.

CNN has not validated the airport's designation as a target.

A CNN team in Kharkiv, Ukraine's second largest city located in the country's northeast, reported hearing a "continuous stream of powerful explosions."

A team in Odessa reported two groups of explosions around 20 minutes apart, while another team in southeastern Zaporizhzhia, which is located along the country's main river, the Dnieper, heard at least one distant explosion. According to two residents of Kramatorsk, they heard at least two enormous explosions in the early hours of Thursday.