Russian troops began entering Ukraine in what was called an “unjustifiable attack” by the British Home Secretary.
Russian President Vladimir Putin announced on Thursday that a military operation had been launched in Ukraine with explosions heard around major Ukrainian cities.
Overnight, kyiv was hit by “horrific rocket fire” and the fighting reached the outskirts of the capital.
Ukraine borders Russia mainly along the north and east where Putin has mobilized his troops.
Russian forces entered through Belarus and Crimea, as well as along the Russian border at Kharkiv.
Ukraine also lost control of the Chernobyl nuclear site, where forces had fought a fierce battle with Russian troops, a presidential adviser in Ukraine has confirmed.
It could be a key site for troops entering kyiv, experts have suggested.
This map shows Russian troop movements and the locations of major target cities.
Ukrainian Foreign Minister Dmytro Kuleba described the incision as “a full-scale attack from many directions”.
Many politicians condemned the invasion, including Prime Minister Boris Johnson who called the invasion “a disaster for our continent”.
He added: “President Putin has chosen the path of bloodshed and destruction by launching this unprovoked attack on Ukraine.
“The UK and our allies will respond decisively.”
Russia has moved its troops across the border into the northeast Chernihiv region that separates kyiv from Belarus, sparking conflict in the country’s capital.
A large airstrike was also confirmed by the Ukrainian authorities at the Antonov international airport of Hostomel, located northwest of kyiv.
The Ukrainian army also said that after heavy fighting it had regained control of the eastern city of Mariupol as fighting continues around Kharkiv – a major eastern city near the Russian border.
In the south, fighting continued, especially near the Crimean peninsula annexed by Russia in 2014.
Ukraine also shares borders with Poland, Slovakia and Hungary to the west, all of which are NATO members, and Romania and Moldova to the south.