Iran’s armed forces chief of staff threatened to close the Strait of Hormuz, a vital shipping route, in response to U.S. sanctions on the regime, which he labeled as “hostility,” reported the semi-official ISNA news agency.

“We are not after closing the Strait of Hormuz, but if the hostility of enemies increase, we will be able to do so,” Mohammad Bagheri told the outlet. “Also, if our oil does not go through the strait, other countries’ oil will certainly not cross the strait, too,” he added.

The strait lies between the Persian Gulf and the Gulf of Oman as the sole maritime passage from the former to the open ocean.

Kuwaiti Deputy Foreign Minister Khaled al-Jarallah expressed alarm over Bagheri’s remarks.

“We are looking at these threats with concern, and hoping as always to distance our region from this tension,” he said, reported the Kuwait News Agency.

The Iranian statement was in response to the United States announcing last week that it will not extend waivers to countries over importing Iranian oil as part of its goal to exert maximum pressure on Tehran.

Japan, South Korea, Turkey, China and India were among the countries that received exemptions for importing Iranian petroleum after U.S. sanctions, including those on Iranian oil, that were lifted under the 2015 Iran nuclear deal, but reimposed last November.

The other recipients—Greece, Italy and Taiwan—have already ended imports of Iranian oil.

The waivers expire on May 2.

“The administration’s decision not to renew oil waivers for any current importer of Iranian oil can be interpreted as a measure of its commitment to its own maximum pressure policy,” said Behnam Ben Taleblu, a senior fellow at the Foundation for Defense of Democracies. “And if the admonition is seeking to not only bring Iran back to the negotiating table but also punish and impede its malign regional activities, then oil, which is the lifeblood of the regime, will have to be targeted in this sort of aggressive fashion.”