Pro-Russian activists stand guard at a barricade as they block access to the Ukrainian Security Service building in the eastern city of Lugansk on Tuesday Russia threatened to force Ukraine’s cash-strapped government to pay in advance for its gas imports, adding fresh pressure to Kiev as it struggled to defuse a stand-off with armed pro-Russian separatists in the country’s east. The prepayment idea was raised by Dmitry Medvedev, Russia’s prime minister, at a meeting of senior officials convened on Wednesday by President Vladimir Putin to discuss a feud over Ukraine’s unpaid gas bills after the country missed a $2.2bn payment on Monday night. “If this critical situation continues, I think we have every reason to move to a system of prepayment for gas supply,” Mr Medvedev said. Mr Putin took a more conciliatory stance, asking the government to “refrain from applying this possibility” until further consultations had taken […]