Iranian navy Adm. Habibollah Sayyari said, as Iran conducts naval drills in the Persian Gulf, that closing the key shipping lane through the Strait of Hormuz would be "very easy."
His comments come as Washington considers new sanctions on business activity through the Iran's Central Bank, where Iran processes most of its oil sales. The European Union is considering an embargo on oil purchases from Iran as punishment for Iran's nuclear program.
Paul Sullivan, an energy and Middle East analyst at Georgetown University, told The Wall Street Journal closing the strait would be a bad move for Iran.
"It's an empty threat that would backfire," he said. "It would devastate the economy of Iran even if they tried it for a very brief period. They would never do it."
Iran is the fourth largest crude-oil producer in the world. It's never closed the strait despite threats to do so during its war with Iraq in the 1980s and following the U.S.-led invasion of Iraq in 2003.