Russia has launched a full-scale invasion of Ukraine after President Vladimir Putin authorised, what he called, a “special military operation” in the east.
The attacks on Thursday came as weeks of intense diplomacy and the imposition of Western sanctions on Russia failed to deter Putin, who had massed between 150,000 and 200,000 soldiers along the borders of Ukraine.
Here are five things you should know about what led to the invasion, what is happening now and what could come next.
[Editor’s note: This explainer, originally published in January, has been updated to reflect the latest developments].
What is the background to the conflict?
Ukraine, which was part of the Russian empire for centuries before becoming a Soviet republic, won independence as the USSR broke up in 1991. It moved to shed its Russian imperial legacy and forge increasingly close ties with the West.
A decision by Kremlin-leaning Ukrainian President Viktor Yanukovych to reject an association agreement with the European Union in favour of closer ties with Moscow led to mass protests that saw him removed as the leader in 2014.
Russia responded by annexing Ukraine’s Crimean Peninsula and throwing its weight behind a separatist rebellion that broke out in Ukraine’s east.
Ukraine and the West accused Russia of sending its troops and weapons to back the rebels. Moscow denied that, saying the Russians who joined the separatists were volunteers.
According to Kyiv, more than 14,000 people have died in the fighting that devastated Donbas, Ukraine’s eastern industrial heartland.
For its part, Moscow has strongly criticised the United States and its NATO allies for providing Ukraine with weapons and holding joint drills, saying that such moves encourage Ukrainian hawks to try to regain the rebel-held areas by force.
Furthermore, Russian President Vladimir Putin has repeatedly said Ukraine’s aspirations to join NATO are a red line, and expressed concern about plans by some NATO members to set up military training centres in Ukraine. This, he has said, would give them a military foothold in the region even without Ukraine joining NATO.
What does Russia want?
It is more about what Russia does not want. Russia does not want Ukraine in NATO – and has said as much in its list of security demands which were sent to the US last December. The demands included a halt to any NATO drills near Russia’s border. It also wants NATO to withdraw from Eastern Europe.
In December, Putin said Russia was seeking guarantees “that would exclude any further NATO moves eastward and the deployment of weapons systems that threaten us in close vicinity to Russian territory”.
Many of these ultimatums have been slammed as non-starters by the West.
Putin, who denied for months that he was planning an invasion, has also called Ukraine an artificial creation carved from Russia by enemies, a characterisation Ukrainians call shocking and false.
Samir Puri, a senior fellow at the International Institute for Strategic Studies, had told Al Jazeera in January that Russia’s aim would likely be to “defeat the Ukrainian armed forces in the field, inflict a crushing military defeat that humiliates the Ukrainians and by extension create concern that the backing Ukraine has from its allies in the West, the US and UK, is insufficient”.
Could Ukraine join NATO?
Ukraine is not a NATO member, but it wants to be. It is considered a partner of the alliance.
Ukraine’s admission to the alliance would require the unanimous approval of the 30 states that make up the body.
Before being considered for membership, NATO says, Kyiv needs to root out scourges such as corruption.
NATO Secretary-General Jens Stoltenberg in December rejected Russian demands to rescind a 2008 commitment to Ukraine that the country would one day become a member.
Analysts however say that NATO allies, mainly the US, are reluctant to expand their military footprint in the region and further jeopardise their relationship with Moscow.
While US Secretary of State Antony Blinken has voiced support for Ukraine’s membership in NATO, President Joe Biden has been more ambiguous on the question.
How did the invasion break out?
Shelling in the Donbas region had intensified since Monday when Putin recognised the two breakaway regions of Donetsk and Luhansk as independent and ordered the deployment of what he called peacekeepers, a move the West called the start of an invasion.
On Wednesday, the separatists issued a plea to Moscow for help to stop alleged Ukrainian aggression – claims the US dismissed as Russian propaganda.
Russia launched a full-scale invasion on Thursday shortly after Putin said he had authorised military action to defend itself against what he said were threats emanating from Ukraine.
Russian missiles hit multiple Ukrainian cities, including Kyiv, as Ukraine reported columns of troops pouring across its borders into the eastern Chernihiv, Kharkiv and Luhansk regions, and landing by sea at the cities of Odesa and Mariupol in the south.
Ukrainian President Volodymyr Zelenskyy declared martial law and appealed to world leaders to impose all possible sanctions on Russia, including on Putin, who he said wanted to destroy the Ukrainian state.
What happens next?
The full scope of the Russian military operation was not immediately clear.
Zelenskyy called on all citizens who are ready to defend the country from Russian forces to come forward, saying Kyiv would issue weapons to everyone who wants them.
The US has predicted that a Russian attack to take Kyiv may cause up to 50,000 civilian casualties, along with that of thousands of Ukrainian and Russian soldiers. European countries have been preparing for the likelihood of hundreds of thousands of Ukrainians fleeing an assault.
President Biden, who has ruled out putting US troops on the ground in Ukraine, said Putin had chosen a premeditated war that would bring a “catastrophic loss of life and human suffering”. He said he would speak to G7 leaders and promised Russia would be held “accountable”.
EU foreign affairs chief Josep Borrell also promised the toughest financial sanctions the bloc had ever imposed.
Washington and London have previously spoken of personal sanctions targeting the Russian president in the event of a major escalation in military action.
Cutting Russia out of the SWIFT financial system, which moves money from bank to bank around the globe, would be one of the toughest financial steps they could take, damaging Russia’s economy immediately and in the long term.
The move could cut Russia off from most international financial transactions, including international profits from oil and gas production, which accounts for more than 40 percent of the country’s revenue.
The US also holds one of the most powerful financial weapons against Putin if he invades Ukraine – blocking Russia from access to the US dollar. The currency still dominates in financial transactions around the world, with trillions of dollars in play daily.
The US is considering imposing export controls, potentially cutting Russia off from the high tech that, among other things, helps warplanes and passenger jets fly and powers smartphones.
Russia has a war chest of more than $600bn in foreign exchange reserves and gold that it can use to prop up the currency and absorb the shock of sanctions.
The prospect of war and sanctions disrupting energy and commodities markets posed an immediate threat to a global economy barely emerging from the pandemic. Stocks and bond yields plunged, while the dollar and gold rocketed higher. Brent oil surged past $100/barrel for the first time since 2014.