European Union foreign ministers have agreed to sanctions against Iran, including a ban on all new oil contracts, the BBC reports. Existing contracts will be honoured until July 1. Exports to the EU represent 20 per cent of the total market for Iran’s oil. The move is intended to pressure Iran over its nuclear program, and is seen as one of the strongest stands the EU has yet taken on a geopolitical matter. Iran has already responded by threatening to block the Strait of Hormuz, through which one fifth of the world’s oil supply passes. The U.S., meanwhile, has said it will keep the passage open, raising concerns of a military confrontation. There are also calls from within Iran to block sales of oil to Europe immediately in retaliation. British Foreign Secretary William Hague said the move demonstrated “the resolve of the European Union on this issue”, while Russian Foreign Minister Sergei Lavrov said, “unilateral sanctions do not help matters,” calling for a resumption of dialogue between the international community and Iran.