The US government announced that it will reimpose sanctions on Iran's oil industry that had been waived under the Iran nuclear deal.
Iran's armed forces have pledged to protect Iranian oil tankers against possible threats after the US said the ships were a “floating liability” and should not be allowed to dock anywhere.
Rear-Admiral Mahmoud Mousavi, a deputy commander of the armed forces, said that they are "prepared today as in the past to protect our fleet of oil tankers against any threats so that it can continue to use marine waterways."
The remarks come days after Brian Hook, the US special representative for Iran, warned Iran’s business partners to “rethink your decision” to buy Iranian oil in the wake of Washington’s “toughest” sanctions against Tehran.
The Trump administration revived all sanctions on Iran's oil, shipping and banking industries that had previously been suspended under a 2015 nuclear deal.
The deputy commander also played down Washington's rhetoric and said the US had used similar threats in the past with little effect.
China, India, South Korea, Japan and Turkey are among the countries set to be given temporary exemptions from the sanctions to ensure crude oil prices are not destabilised.
Both Russia and China have vowed to continue purchasing Iranian oil and ignore US sanctions.