Here are the top 10 updates on this big story:
The Russian defence ministry said it has destroyed air bases, air defences in Ukraine with precision weapons. "Military infrastructure at Ukrainian army air bases has been rendered out of action," it said in a statement carried by news agencies, which added that Kyiv's air defence systems were "eliminated".
Ukraine also claimed that it has downed five Russian planes and a helicopter in the east of the country near a rebel-held enclave.
The European Union said that it will hold Russia "accountable" for its attack on Ukraine and is preparing fresh sanctions that will deal "massive and severe consequences" to Moscow.
The decision to launch a military operation was taken to "defend separatists" in eastern Ukraine, Mr Putin said in a nationally televised address earlier today. Warning against foreign interference, he said Russia will "aim for demilitarization and denazification of Ukraine."
Mr Putin's announcement came just hours ahead of a special emergency session in the UN Security Council. The meeting was scheduled after Mr Putin recognised the independence of Ukraine's breakaway regions.
Earlier, Ukraine's President Volodymyr Zelensky had made an emotional late-night appeal to Russians not to support "a major war in Europe". Speaking Russian, Mr Zelensky said that the people of Russia are being lied to about Ukraine and that the possibility of war also "depends on you".
Mr Putin has recognised the independence of the Ukraine breakaway regions of Donetsk and Lugansk and has signed friendship treaties with them, inviting strong criticisms from the US and its allies.
"Who in the Lord's name does Putin think gives him the right to declare new so-called countries on territory that belongs to his neighbours?" Mr Biden said as he announced economic sanctions against Russia. The US has said it would continue to supply "defensive" weapons to Ukraine and deploy US troops to reinforce NATO allies in eastern Europe. The steps are expected to bolster the now more than 90,000 US troops temporarily or permanently deployed in Europe.
India has asked "all sides" to exercise "utmost restraint", saying the mounting crisis can only be resolved through diplomatic dialogue.
Russia has repeatedly rejected US allegations that it intends to invade Ukraine as "hysteria" and propaganda. The Donetsk and Luhansk separatists reportedly hold about 30% of the territory of the two Ukrainian regions as of Wednesday, with the rest under the control of government forces.
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