With reporting by AFP and AP

EU officials have warned Armenia that its decision to join a Russia-led trade union may thwart its chances to sign a key political and economic agreement with the bloc.Foreign Minister Linas Linkevicius of Lithuania, the current EU president, said the EU respects Yerevan's decision to join the Customs Union of Russia, Belarus, and Kazakhstan, but said Armenia "cannot enter both organizations at the same time."Swedish Foreign Minister Carl Bildt, on his Twitter account, spoke of a "U-turn" and also said, "Now President [Serzh Sarkisian] prefers Kremlin to Brussels."Sarkisian announced his intention to join the Customs Union after talks with Russian President Vladimir Putin in Moscow on September 3. He said Armenia is also ready to take part in the establishment of the Eurasian economic union but said the moves do not constitute a “refusal to continue our dialogue with European structures.”Sarkisian made no mention of the planned Association Agreement with the EU.EU officials have repeatedly made clear that the Association Agreement, which includes a free-trade agreement with the EU, is "not compatible" with possible Armenian membership in the Customs Union.Armenia had been poised to initiate an Association Agreement with the EU at a November summit in Vilnius.Russia, Belarus, and Kazakhstan founded the Customs Union in 2010 as a counterweight to the EU’s economic sphere.They launched the so-called Common Economic Space last year and said the goal was to set up by 2015 a Eurasian economic union modeled after the EU. Moscow has been pushing several former Soviet republics to join the process.In a statement on September 3, Linkevicius and seven other ministers from Nordic and Baltic countries warned against Russian pressure on post-Soviet states.They said that "any economic threat or political pressure directed against [the European Union's] Eastern partners because of their European aspirations and engagement with the EU is unacceptable."