A member of Iran’s parliament said on Monday that the country’s military was set to practice its ability to shut the narrow Strait of Hormuz which provides access to the Persian Gulf.

The announcement comes a month after Iran’s energy minister warned that Tehran could use oil as a weapon in the event of conflict. The Iranian armed forces declined comment to the Reuters news agency.

The legislator, Parviz Sarvari, who is a key member of parliament’s national-security and foreign-policy committee, told the student news agency ISNA, “Soon we will hold a military maneuver on how to close the Strait of Hormuz. If the world wants to make the region insecure,” he added, “we will make the world insecure.”

40 percent of the world’s seaborn oil transports passes through the narrow strait every day. Large quantities of liquefied natural gas are also exported from Qatar through this critical waterway.

The United States receive about a quarter of their imported oil from countries bordering the Persian Gulf. Asian buyers include China, Japan and South Korea.

Iran’s ability to permanently close the Strait of Hormuz would be hampered by the powerful US Navy presence in the region. Thirty ships patrol the Persian Gulf and nearby waters.

The Iranian strategy would probably be aimed at harassing oil tankers with diesel submarines and shore batteries and thus make it nigh impossible for the less than two dozen supertankers that traverse the strait every day to deliver their oil and gas transports to the world. This would put 20 percent of the world’s oil supply at immediate risk.

Even if American intervention should break an Iranian blockade within days, oil prices and insurance rates will skyrocket around the world and impact the fragile economies of the West.

A prolonged naval battle could cause shortages across the developed world as global strategic reserves are estimated to be able to replace Persian Gulf oil supply for less than a month.