Ukraine president says he will provide weapons to any citizen who wants to defend the country

• Russia has launched attacks on Ukraine, with reports of explosions across the country.
• Ukrainian President Volodymyr Zelensky called on citizens to fight on Thursday morning.

Ukrainian President Volodymyr Zelensky on Thursday says he would provide weapons to any citizen who wants to defend the country against Russian attacks. "We will give weapons to anyone who wants to defend the country. Be ready to support Ukraine in the squares of our cities," Zelensky tweeted.

Russia attacked Ukraine early Thursday morning, with reports of explosions across the country, including its capital Kyiv.

The scope of the Russian attack appears to be huge, with Ukraine's foreign minister saying the country was launching a "full-blown invasion" on Ukraine from multiple sides. Strikes and explosions have occurred in both the west and the east of the country, not just the eastern Donbas and Donetsk regions which have long been subject to unofficial Russian military intervention.

Zelenzky also said that Ukraine severed diplomatic relations with Russia and urged Russians to come out and protest against the war.

"For all those who have not yet lost their conscience in Russia, it is time to go out and protest against the war with Ukraine," he tweeted.

Earlier on Thursday, Zelensky, who declared martial law, urged citizens to stay calm. "Stay calm, stay at home, the army is doing its work," he said in a video address to the country, "Don't panic. We are strong. We are ready for everything. We will defeat everyone. Because we are Ukraine."

In and speech at 6 a.m Moscow time, Russian President Vladimir Putin said the military operation would be intended to "demilitarize" Ukraine, but not to occupy it.

Shortly after his speech, Russian tanks crossed the border from Belarus in the north and occupied Crimea in the south into Ukraine, according to reports citing the Ukraine Interior Ministry.

What's happening in Ukraine?

Russia's conflict with Ukraine has been rumbling for years but escalated dramatically in recent weeks.

Russia assembled vast numbers of troops around Ukraine — as many as 190,000, per US estimates — in the largest military operation in the region since World War II.

On Monday, Putin recognized the claims to independence of the breakaway Luhansk and Donetsk areas of Ukraine, ordering troops there for what he described as a limited peace-keeping operation in the east of the country.

Less than 72 hours later, Putin authorized a full-scale attack on Ukraine. In the hours that followed, explosions pounded cities around Ukraine, many hundreds of miles from the previous conflict zone. Ukrainian officials reported fighting on its borders with Russia, and dozens of casualties.The new wave of hostilities expanded the clash from a limited incursion over disputed land into the most serious armed conflict in Europe for at least a decade.

• Insider's live blog of the invasion is covering developments as they happen.