Russian President Vladimir Putin warned leaders in Europe on Thursday that Russia could cut supplies of natural gas to Ukraine if its unpaid bill isn’t addressed, potentially disrupting deliveries to the rest of the continent. In a letter sent to leaders in countries reliant on Russian gas, Mr. Putin ramped up pressure on the fledgling government in Kiev, repeating his threat that Russia may have to take the “extreme measure” of making Ukraine pays in advance for the gas it uses. He called for emergency talks with Europe to resolve the matter. “In the event of further violation of the conditions of payment, [state-run gas company Gazprom] will completely or partially cease gas deliveries,” the letter stated. “We fully realize that this increases the risk of siphoning off natural gas passing through Ukraine’s territory and heading to European consumers. We […]