Ukraine’s Interior Minister has warned separatists occupying state buildings in its eastern regions to leave within two days or face forced eviction, risking the anger of Moscow which has warned against any violence towards pro-Russian protesters.
Security forces have so far refrained from using force in the cities of Donetsk, Luhansk and Kharkiv, wary of warnings from Russia that military action remains on the table if ethnic Russians come under attack.
But the Interior Minister, Arsen Avakov, was clear that the occupations which began on Sunday would not be tolerated for much longer. "I want to repeat that there are two options: political settlement through negotiations and the use of force," Mr Avakov told reporters. "We are ready for both options."
Ukrainian, British and American officials have blamed Russia for stoking unrest in the three cities, potentially to create a pretext for an incursion similar to Moscow's annexation of Crimea last month. But the threat of force is not the only lever Russia wields: Ukraine is also heavily reliant on its neighbour for energy, raising fears Moscow could cut supplies as tensions escalate.
Authorities in Kiev failed to meet a deadline earlier this week to start repaying a £1.3bn bill to Russian state energy firm Gazprom. The Russian Prime Minister, Dmitry Medvedev, said that there were now grounds for insisting on upfront payments - something Ukraine cannot afford.
President Vladimir Putin, however, said he was willing to hold further consultations. "Taking into account the complex situation in Ukraine and the fact that we have not yet finished talks with the EU, I would ask Gazprom and the government to hold off on such a possibility," he said.
Ministers and officials from the US, Russia, EU and Ukraine are due to hold talks on the crisis next week, the first such joint negotiations since the crisis began in November, when then-President Viktor Yanukovych backed out of a trade agreement with the EU.
It was offers of generous loans and cut-price gas that helped convince Mr Yanukovych to steer his near- bankrupt nation back towards Russia. That decision sparked the protests which eventually led to the ousting of Mr Yanukovych's in February, and Moscow has not been so forgiving with the new pro-EU administration that took his place.
Prices for gas have gone up and pressure is mounting on other European nations to come up with alternative supplies, both for Ukraine and themselves, with nearly half of the EU's gas imports from Russia transiting through Ukraine. The tug-of-war over Ukraine's future has sent relations between the West and Russia to lows not seen since the end of the Cold War, with Russia's annexation of Crimea sparking a round of sanctions against dozens of Russian and Ukrainian officials.
European and US officials have in the past few days issued fresh warnings to Russia to stay out of Ukraine's affairs or face much broader economic sanctions. They accuse Moscow of covertly backing the hundreds of separatist protesters that stormed the state buildings on Sunday.
The protesters are demanding referendums on independence similar to the one held in Crimea, but their calls do not have the backing of the majority of residents, many of whom are ethnic Ukrainians and are hoping presidential elections scheduled for the end of May may bring some stability.
Police have cleared protesters from the buildings in Kharkiv, but separatists have barricaded themselves behind tyres and razor wire in Donetsk and Luhansk.
Russia has denied any involvement in the events in eastern Ukraine, and today issued a statement saying the US and Ukraine had "no reason to be worried" about the reported build up of tens of thousands of troops along its border with Ukraine.
"Russia has stated many times that it is not carrying out any unusual or unplanned activity on its territory near the border with Ukraine that would be of military significance," the statement read.
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