The dispute focuses on the Soviet-era Druzhba  pipeline system that supplies 10% of the European Union’s oil.  Poland depends on the Druzhba pipeline for most of its crude oil. Germany received about 15% of its crude through the pipeline in 2008.

Russia began curbing supplies through the pipeline to Belarus’s domestic market after an oil-supply agreement between the two countries expired Dec. 31. On Monday, Russian officials said those deliveries had been resumed, but not before Belarus threatened to cut off electricity to Russia’s westernmost region if the Russians insisted on imposing a new tax on the oil Belarus processes for export.

Three years ago, Russia briefly cut oil exports to the European Union nations through a Belarussian pipeline as the two former Soviet republics quarreled over price. That shutdown, along with a January 2009 natural-gas cutoff to Europe caused by contract disputes with Ukraine, has raised doubts in Europe about Russia’s dependability as a top energy supplier.