Russian President Vladimir Putin has officially ordered an invasion of Ukraine and issued a chilling warning to other countries contemplating getting involved.
Nine News is reporting there are already reports of hundreds of casualties.
At this stage, President Putin has said he has no plans to occupy the Ukrainian capital, Kyiv, or the wider country, but said he intended to 'demilitarise' and 'de-Nazify' Ukraine.
He called on Ukrainian soldiers to throw down their weapons and go home.
He also warned that any attempt to interfere by outside nations would lead to 'consequences greater than any of you have faced in history'.
"All relevant decisions have been taken. I hope you hear me," he added.
In the televised address, Putin also accused the US and its allies of failing to offer Moscow security guarantees and ignoring Russia's demands that Ukraine not join NATO - the North Atlantic Treaty Organisation - which boasts 30 member states across North America and Europe.
Putin has been demanding that Kyiv renounce its bid to join NATO.
He also wants Ukraine to demilitarise Crimea and recognise Russia's sovereignty over the region.
US President Joe Biden denounced the action and said the world will 'hold Russia accountable'.
The Polish Prime Minister, Mateusz Morawiecki, similarly called for swift and sharp action.
"We must immediately respond to Russia's criminal aggression on Ukraine," he wrote on Twitter.
"Europe and the free world has to stop Putin.
"Today's European Council should approve fiercest possible sanctions.
"Our support for Ukraine must be real."
The UK Prime Minister, Boris Johnson, said Putin had chosen 'a path of bloodshed and destruction'.".
"I am appalled by the horrific events in Ukraine and I have spoken to President Zelenskyy to discuss next steps," he said.
"The UK and our allies will respond decisively," he added.
Linda Thomas-Greenfield, the US ambassador to the United Nations, called on Russia to end things now.
"Tonight, we're seeing the Russians close airspace, move troops into Donbas and move forces into combat-ready positions. This is a perilous moment, and we're here for one reason and one reason only - to ask Russia to stop. Return to your borders. Send your troops and your tanks and your planes back to their barracks and hangers."
Antonio Guterres, the UN's secretary general, meanwhile, begged for peace.
"I have only one thing to say, from the bottom of my heart, President Putin, stop your troops from attacking Ukraine.
"Give peace a chance."
Featured Image Credit: Alamy