Dozens of people are feared dead and many more injured after Russia launched a full scale invasion of Ukraine.
Following a fiery address by Vladimir Putin last night, troops and tanks rolled in over the north and south borders and shells were launched into cities.
Blasts and explosions rang out in cities including capital Kyiv overnight before harrowing photos of casualties began to emerge this morning.
As Western countries prepare to respond to the invasion, this is how invasion broke out overnight and turned into war.
Click here to follow our live blog with the latest updates on the conflict.
Volodymyr Zelensky urges Russia not to attack
Hours before the invasion began, the President of Ukraine made a televised address imploring Russia not to attack.
"We know for sure that we don’t need the war," he said.
"Not a Cold War, not a hot war. Not a hybrid one. But if we’ll be attacked by the (enemy) troops, if they try to take our country away from us, our freedom, our lives, the lives of our children, we will defend ourselves.
"Not attack, but defend ourselves. And when you will be attacking us, you will see our faces, not our backs, but our faces."
Vladimir Putin makes bleak warning to West as invasion begins
At 6am Moscow time (3am GMT), the Russian President said that his troops would 'demilitarize' and 'de-Nazify' Ukraine.
He urged Ukrainian service members to lay down their arms and go home, before warning that clashes between the two sides was now 'inevitable'.
"To anyone who would consider interfering from the outside - if you do, you will face consequences greater than any you have faced in history," he said.
Air strikes on Ukraine begin
At around 5am local time the first missiles began to fall on military facilities across Ukraine.
Cities have also been targeted, with a huge explosion ringing out in Kyiv and the eastern city of Kharkiv being hit.
Ukrainian soldiers have been photographed inspecting a shell in Kyiv, which was a non-targeted projectile according to some reports which contradict Russian claims that its only using high-precision missiles.
Photos from the scene show rubble spread across the the road in the capital after a military building there was hit.
In Donbas, which is in the separatist Donetsk region, a man was seen weeping above the body of a person thought to be his son apparently killed in one of the strikes.
Later on a blast rang out in the city of Ivano-Frankivsk in the west of Ukraine, with reports suggesting that the airport there had been targeted by missile strikes.
Officials have said an attack on a military unit in Podilsk, outside Odessa, killed six people and wounded seven.
An apartment block in Chuhuiv in the north east has been completey gutted by a blast which knocked out all the windows and tore down its balconies.
According to analysis by Bellingcat, the apartment block was likely hit by mistake due to its proximity to a nearby airport.
Russian troops land in Ukrainian cities
The Russian military pushed further into Ukraine from the north and south as the missiles rained down.
Interfax reported that soldiers had landed in the Ukrainian cities of Mariupol in the south east and and Odessa on the Black Sea.
Troops atop a column of military vehicles entered Ukraine from a border crossing with Belarus to the north, CNN reported at around 6.48am local time.
President of Ukraine defiantly says country will win conflict with Russia
"Russia conducted strikes on our military infrastructure and our border guards. There were blasts heard in many cities of Ukraine," Volodymyr Zelensky said hours after the shelling first began.
"We’re introducing martial law on the whole territory of our country.
“A minute ago I had a conversation with President Biden. The US have already started uniting international support.
"Today each of you should keep calm. Stay at home if you can. We are working. The army is working. The whole sector of defence and security is working,” he added.
“No panic. We are strong. We are ready for everything. We will win over everybody because we are Ukraine.”
Boris Johnson pledges to act "decisively"
Just before 5am GMT, around the time President Zelensky declared martial law, the UK's PM condemned the attack and pledged to support Ukraine.
"I am appalled by the horrific events in Ukraine and I have spoken to President Zelensky to discuss next steps," he tweeted.
"President Putin has chosen a path of bloodshed and destruction by launching this unprovoked attack on Ukraine. The UK and our allies will respond decisively."
At 7.30am the PM chaired a meeting of Cobra ahead of an address to the nation and statement to the Commons later today.
Ukraine hits back at Russian troops
Ukraine’s military has said it had destroyed four Russian tanks on a road near the eastern city of Kharkiv, according to Reuters.
It claimed to have killed 50 troops near a town in Luhansk region and downed a sixth Russian aircraft, also in the country’s east.
Russia has denied reports that its aircraft or armoured vehicles have been destroyed.
Ukraine’s border guard service said that three of its servicemen had been killed in the southern Kherson region and that several more were wounded.
Commercial air traffic into and out of Ukraine grinds to a halt
Whizz Air, a Hungarian airline which typically has many services into and out of Ukraine, has said it will be stopping these flights as Ukrainian airspace is shut down.
"Due to the current events in Ukraine and the airspace closure, Wizz Air regrets to inform our customers that the airline must temporarily suspend all flight operations in the country," it said.
Up until now, commercial routes out of the country had been available to those hoping to leave.
Airline Ryanair has also suspended flights to Ukraine, for at least the next two weeks.
Ryanair said: "Due to the closure of Ukrainian airspace overnight, and the apparent invasion by Russian forces all Ryanair flights to/from Ukraine have been suspended for at least the next 14 days.
President of Ukraine urges his people to donate blood
After holding a meeting with his minister this morning, at around 9am GMT Volodymyr Zelensky made a plea for any Ukrainians with military experience to joint the country's defence.
The government will provide weapons to people who want them, he said, before urging people to donate blood to help injured hospitals.
Ukraine has now severed diplomatic ties with Russia, the president confirmed.
"We will fight for our country and we will support our country in the squares of each town," he said.
Boris Johnson calls for urgent Nato meeting
The UK's PM has called for the allied Western forces to meet as soon as possible.
"This is a catastrophe for our continent," he tweeted.
"I will make an address to the nation this morning on the Russian invasion of Ukraine. I will also speak to fellow G7 leaders and I am calling for an urgent meeting of all NATO leaders as soon as possible."
His comment came shortly after a siren was heard in the Polish town of Medyka, according to Reuters.
The town acts a border crossing between Poland, a Nato member, and Russia.
EU leaders will hold an emergency meeting later today to discuss further sanctions on Russia, with the leaders will be considering "massive and severe consequences".
