Russia and Serbia have signed a series of energy agreements that are being hailed as historic.Russian President Dmitry Medvedev put pen to paper at the Kremlin alongside his Serbian counterpart, Boris Tadic. In one key accord, the Russian energy giant Gazprom secures a 51 percent stake in the Balkan country’s oil monopoly, NIS. Some Serbian politicians claim that the 400 million euro price being paid is not enough. Analysts have said that, given Moscow’s support for Belgrade in the row over Kosovo’s self-declared independence, the deal was largely politically motivated. Gazprom, meanwhile, is flexing its muscles, warning that it will cut off supplies to Ukraine unless debts are paid by the end of the year.