EU concerned by Armenian plans to join Russia’s Customs Union

The unpredictable decision by Armenia’s President Serzh Sargsyan that Yerevan will join a customs union with Russia has raised doubts over Armenia’s EU integration path and caused concern in Brussels about Europe’s relations with its eastern neighbours.

Armenia was poised to sign a key political and free-trade deal with the EU at a summit in November but both Russia and the EU have said countries can’t have both.

Armenia’s decision prompted a planned debate and vote at the European Parliam...