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Russian President Vladimir Putin has ordered his troops to carry out a special military operation in the Donbas region of Ukraine, Russian news agencies said on Thursday.
Donbas, in the country's east, has been at the centre of the escalating crisis between Russia and Ukraine.
Russian-backed separatists in Donetsk and Luhansk — collectively known as the Donbas region — broke away from Ukrainian government control in 2014 and proclaimed themselves independent "people's republics".
Tension had been brewing after Mr Putin signed a decree on Monday recognising the two breakaway enclaves.
Where is Ukraine's Donbas region?
Donbas is a region in south-eastern Ukraine occupied by the Donetsk People's Republic and the Luhansk People's Republic separatist groups. Its name is a combination of the words Donets and Basin, referring to the coal-mining region along the Donets River.
What does Russian recognition of Donbas mean?
For the first time, Russia is saying it does not regard Donbas as part of Ukraine. That could pave the way for Moscow to send military forces into the separatist enclaves, using the argument that it is intervening to protect them from Ukraine.
Alexander Borodai, a Russian parliament member and former Donetsk political leader, told Reuters last month that the separatists would then look to Russia to help them wrest control of parts of the two enclaves that are still under the control of Ukrainian forces.
If that happens, it could lead to open military conflict between Russia and Ukraine.
What about the Minsk peace process?
Russian recognition effectively kills off the 2014-15 Minsk peace agreements that, although still not enforced, have until now been considered by all sides, including Moscow, as the best chance for a peaceful resolution. The accords call for a large degree of autonomy for the two enclaves inside Ukraine.
How will the West respond?
Western governments have been lining up for months to warn Moscow that any movement of military forces across the Ukrainian border would draw a strong response, including stringent financial sanctions.
US Secretary of State Antony Blinken said last week that recognition "would further undermine Ukraine’s sovereignty and territorial integrity, constitute a gross violation of international law, [and] call into further question Russia’s stated commitment to continue to engage in diplomacy to achieve a peaceful resolution of this crisis".
He said it would necessitate a "swift and firm" response from the US and its allies.
How has Russia supported the Donbas region?
Former Russian president Dmitry Medvedev said on Monday that Moscow had issued 800,000 Russian passports to Donbas residents since Mr Putin signed an order in April 2019 allowing them to apply for citizenship under an expedited procedure.
The EU, at the time, said the measure was an attack on Ukrainian sovereignty while Ukrainian President Volodymyr Zelenskyy called for more sanctions against Moscow.
In May 2021, Mr Zelenskyy described Moscow's initiative as a first step towards the annexation of the region.
A former senior official from the self-proclaimed Donetsk People's Republic told Reuters in 2016 that Russia directly finances pensions and public sector salaries in the two enclaves.
After war broke out, Kiev stopped paying wages to civil servants registered as living in separatist-controlled enclaves. Much of the heavy industry on which the Donbas region depends on for revenue has stopped operating.
However, Moscow said it does not bankroll the separatist administrations.
Russian rouble and schooling
Both enclaves have abandoned the Ukrainian currency in favour of the Russian rouble as their official currencies.
Local schools now follow the Russian national curriculum instead of Ukraine's.
In 2021, the Donetsk People's Republic marked Russia Day on June 12 to commemorate Russia's declaration of independence from the Soviet Union.
Reuters contributed to this report.