Russian energy giant Gazprom will be compelled to switch over to prepaid gas deliveries to Ukraine or completely cut off natural gas supplies, should the country further violate its terms of payment, Russian President Vladimir Putin wrote Thursday in an open letter to 18 European leaders. “Gazprom is compelled to switch over to advance payment for gas deliveries, and in the event of further violation of the conditions of payment, will completely or partially cease gas deliveries,” Putin explained, saying this was undoubtedly an extreme measure. Talk of a gas cutoff came as Ukraine again defaulted on its gas debt in March, swelling past the November record of $1.45 billion. Putin explained that Gazprom’s decision to switch to upfront payments for gas stemmed from Ukraine’s inability to pay its debts, despite unprecedented price cuts that Kiev had been recently enjoying. “I would like to draw your attention to the fact that in March there was still a discount price applied, that is [the price was] $268.50 per 1,000 cubic meters of gas. And even at that price, Ukraine did not pay a single dollar,” the president said. More