Russia launched its invasion by land, air and sea on Thursday following a declaration of war by President Vladimir Putin.
Putin, who denied for months that he was planning an invasion, has declared in a televised address that he had ordered “a special military operation” to protect people, including Russian citizens who had been subjected to “genocide” in Ukraine. He also says Ukraine is an illegitimate state whose lands historically belong to Russia.
The West has long described the accusations as “absurd propaganda”.
What’s the issue between Russia and Ukraine?
Ukraine, a democratic country of 44 million people with more than 1,000 years of history, is the biggest country in Europe by area after Russia itself.
It voted overwhelmingly for independence from Moscow after the fall of the Soviet Union and says it aims to join Nato and the European Union.
Putin, meanwhile, has called Ukraine an artificial creation carved from Russia by enemies, a characterisation Ukrainians call shocking and false. The Russian President has also claimed that Ukraine is a puppet of the West and was never a proper state anyway.
Live updates: Ukraine crisis
Putin has demanded guarantees from the West and Ukraine that it will not join Nato, a defensive alliance of 30 countries. He also wants Ukraine to be demilitarised and become a neutral state.
But in January last year, Ukrainian President Volodymyr Zelenskyy urged US President Joe Biden to let Ukraine join Nato.
This greatly irked Russia as it does not want Ukraine to move towards European institutions such as Nato and the EU.
But why do Russia, US and Europe care so much about Ukraine?
Both Russia and the West see Ukraine as a potential buffer against each other.
Russia considers Ukraine within its natural sphere of influence. Most of it was for centuries part of the Russian Empire, many Ukrainians are native Russian speakers and the country was part of the Soviet Union until winning independence in 1991.
Russia was unnerved when an uprising in 2014 replaced Ukraine’s Russia-friendly president with an unequivocally Western-facing government.
Most former Soviet republics and allies in Europe had already joined the European Union or Nato. Ukraine’s lurch away from Russian influence felt like the final death knell for Russian power in Eastern Europe.
The uprising in 2014
When Ukraine’s Moscow-friendly president was driven from office by mass protests in February 2014, Russia had responded by annexing Ukraine’s Crimean Peninsula.
It then threw its weight behind an insurgency in the mostly Russian-speaking eastern Ukraine region known as Donbas.
In April 2014, Russia-backed rebels seized government buildings in the Donetsk and Luhansk regions, proclaimed the creation of “people’s republics” and battled Ukrainian troops and volunteer battalions.
The following month, the separatist regions held a popular vote to declare independence and make a bid to become part of Russia. Moscow hasn’t accepted the motion, just used the regions as a tool to keep Ukraine in its orbit and prevent it from joining NATO.
Ukraine and the West accused Russia of backing the rebels with troops and weapons. Moscow denied that, saying any Russians who fought there were volunteers.
Amid ferocious battles involving tanks, heavy artillery and warplanes, Malaysia Airlines Flight 17 was shot down over eastern Ukraine on July 17, 2014, killing all 298 people aboard. An international probe concluded that the passenger jet was downed by a Russia-supplied missile from the rebel-controlled territory in Ukraine. Moscow still denied any involvement.
What do Ukrainians want?
The threat of another Russian invasion has consolidated a growing sense of national pride and unity among Ukrainians, even among those who grew up speaking Russian.
As recently as 2001, opinion polls suggested that roughly half of Ukrainians supported the country’s departure from the Soviet Union. Today, more than 80% support Ukraine’s independence, and more than half back joining Nato.
Though anxiety courses through the country, life continues more or less as normal in most of it. Both civilians and government leaders say that they remain calm amid foreign reports of an imminent invasion, and some even say they doubt that Russia will actually invade. But at the same time, many civilians have increasingly joined volunteer defence units and signed up for first-aid courses.
(With inputs from agencies)