Russian President Vladimir Putin on Thursday authorised a "special operation" in Ukraine's Donbass region, media reports have claimed.
Quoting the Russian state news agency TASS, Xinhua news agency reported that the operation has begun.
"We are hearing reports - some unconfirmed - of explosions in other parts of the Ukraine. Loud bangs in the capital Kyiv as well as Kramatorsk in the Donetsk region," BBC news reported.
But there have also been reports on social media of explosions in Ukraine's Kharkiv in the north-east, Odesa in the south, and the eastern Donetsk Oblast area.
Reports also said that Putin has urged the Ukrainian soldiers in eastern Ukraine to lay down weapons and return to their homes.