The U.S. military warned it would not let Iran close off a key Persian Gulf waterway to oil shipments as an Iranian admiral said such a move would be easy. \"The free flow of goods and services through the Strait of Hormuz is vital to regional and global prosperity,\" said U.S. Navy spokeswoman Lt. Rebecca Rebarich of the Fifth Fleet, based in Manama, Bahrain, about 100 miles from Iran\'s coastline. \"Anyone who threatens to disrupt freedom of navigation in an international strait is clearly outside the community of nations,\" she said. \"Any disruption will not be tolerated.\" Her statement followed two days of threats by Iran to shut the strategic waterway to all oil shipments if the West imposes sanctions on Iran\'s oil exports. Iranian First Vice President Mohamed Reza Rahimi said Tuesday, \"If they impose sanctions on Iran\'s oil exports, then even one drop of oil cannot flow from the Strait of Hormuz.\" Iran\'s official Islamic Republic News Agency quoted him as saying Iran had \"no desire\" for hostilities, but \"our enemies will give up on their plots against Iran only if we give them a firm and strong lesson.\" Adm. Habibollah Sayyari, commander of the Iranian navy, followed up Wednesday, telling the state-run Press TV 24-hour news channel hamstringing the global oil supply by closing the strait would \"be easier than drinking a glass of water.\" The narrow strait, which includes Iranian territorial waters, is a vital artery for transporting about a third of the world\'s tanker-borne oil and about 17 percent of all world oil shipments. About 13 tankers carrying 15.5 million barrels of crude oil pass through the strait on an average day, including crude from Iran, Iraq, Kuwait, Saudi Arabia and the United Arab Emirates. The threats came as President Barack Obama prepared to sign legislation that could substantially reduce Iran\'s oil revenue, in a bid to deter Tehran from pursuing a nuclear weapons program. U.S. and European officials, supported by the International Atomic Energy Agency, allege Tehran is planning to build nuclear weapons. Iran, the world\'s No. 3 energy exporter, relies on oil exports to finance as much as half its national budget. The U.S. legislation, passed by Congress, would penalize foreign corporations that do business with Iran\'s central bank, which collects payments for most of the country\'s energy exports. The sanction would make it difficult for those who do business with the central bank to also do business with the United States, The New York Times said. The bill includes loopholes to reduce the penalties on close allies that support pressuring Iran to abandon its nuclear program. Iranian officials insist their goal is to generate electricity without dipping into the oil supply they prefer to sell abroad, and to provide fuel for medical reactors. The IAEA published a report last month that for the first time laid out evidence Iran may be secretly working to design a nuclear warhead. The European Union says it will consider imposing its own strict new sanctions against Iran, including an embargo on Iranian oil, next month. EU countries receive 450,000 barrels a day of Iranian oil.