Tehran has said it will establish a “restricted zone” outside the Strait of Hormuz within days, after a weekend escalation during which the US struck three Iranian oil tankers and Iran attacked American warships.
Mohsen Rezaei, secretary of Iran's Supreme National Security Council, said the zone would begin at the US blockade line and extend into parts of the Gulf.
“Any ship entering the new zone will be added to a sanctions list,” he said in an interview with state television late on Sunday.
Mr Rezaei also said Iran and Oman had agreed on a new shipping corridor through the Strait of Hormuz. He provided no co-ordinates for the proposed zone and gave no details on how the threatened sanctions would be imposed.
“The maps of a new international corridor which lies in Iranian and Omani waters and in which Iran will have management have been agreed and should be signed in the coming days,” he said.
The purported memorandum has been under discussion between Iran and Oman since a fragile ceasefire took effect in mid-June. It has not been published, however.
“We will only commit to the Strait of Hormuz being open when they [the Americans] stop the sabotage, threats and attacks on Iran,” Mr Rezaei said.
An analysis circulating alongside Mr Rezaei's statement suggested the proposed zone could extend Iranian oversight towards vessels entering the Gulf of Oman.
The accompanying map depicts a potentially broad area, but it is not an official Iranian maritime chart and cannot establish the precise boundaries Tehran intends to impose. It is also unclear what legal or operational mechanism Iran would use to enforce sanctions against vessels entering the zone.
The apparent aim is to create uncertainty around access to the Gulf. By threatening sanctions against vessels entering an area it claims to control, Tehran could increase risks for shipowners, insurers and traders while continuing to argue that the Strait of Hormuz itself remains open.
Traffic through the waterway has already fallen sharply. An average of about 10 commodity ships has crossed the strait daily over the past 10 days, the lowest level since May. Brent crude rose above $97 a barrel on Monday.
The US struck three Iranian oil tankers on Saturday, including one off Kharg Island, according to Central Command, following attacks by Iran's Islamic Revolutionary Guard Corps on American warships.
Last week, Iranian Parliament Speaker Mohammad Bagher Ghalibaf said the era of “proportional responses” had ended. He warned that future attacks on Iranian interests would receive a “faster, heavier and more painful response”.
