The chairman of Iran’s Joint Chiefs of Staff says the decision over whether Tehran would block the strategic Strait of Hormuz, the passageway through which a fifth of the world’s oil flows, rests in the hands of the country’s Supreme Leader Ayatollah Ali Khamenei.

Gen. Hasan Firouzabadi says Iran has a contingency plan to close the key route, but Khamenei, as commander in chief of the armed forces, would have to make the final decision.

Firouzabadi’s comments come two weeks after the European Union enforced a total oil embargo against Iran for its refusal to halt its uranium enrichment program. His comments were reported by the semi-official Fars news agency Sunday.

Iran’s Revolutionary Guard has previously warned that Tehran would order the closure if the country’s oil exports were blocked.