The US on Thursday warned Iran against disrupting oil shipments at the mouth of the vital Persian Gulf waterway, after Tehran threatened to shut the Strait of Hormuz if the West imposed sanctions on its crude exports.
"This is not just an important issue for security and stability in the region, but is an economic lifeline for countries in the Gulf, to include Iran," Pentagon Press Secretary George Little said.
About 40 % of the world's tanker-borne oil passes through the Strait of Hormuz which links the Gulf - and the oil-producing states of Bahrain, Kuwait, Qatar, Saudi Arabia and the United Arab Emirates (UAE) - to the Indian Ocean.
"Interference with the transit or passage of vessels through the Strait of Hormuz will not be tolerated," Little said in a strongly worded message to Iran.
Little's remarks came after Iranian Vice-President Mohammad Reza Rahimi warned that "not a drop of oil will pass through the Strait of Hormuz" if sanctions are widened and Iran's navy chief Admiral Habibollah Sayari said that closing the strait would be "easier than drinking a glass of water"
Iranian navy has been staging wargames in international waters to the east of the strait which at its narrowest is just 34 miles wide.
"The free flow of goods and services through the Strait of Hormuz is vital to regional and global prosperity," said Navy 5th Fleet in Bahrain spokeswoman Cmdr. Amy Derrick Frost.
"Anyone who threatens to disrupt freedom of navigation in an international strait is clearly outside the community of nations; any disruption will not be tolerated," she said.
Derrick said the 5th Fleet which is based in Bahrain, maintains a robust presence in the region to deter or counter destabilising activities.