The shipping industry was placed on high alert on June 22, with warnings that Tehran could retaliate against commercial vessels following after U.S. airstrikes against Iran’s nuclear facilities.

Greece, home to more oil oil-tanker capacity than any other nation, cautioned its ship owners to think again if considering entering the Persian Gulf in the wake of U.S. airstrikes. Vessels planning to sail through the Strait of Hormuz, the waterway that sits at the mouth of the region, should “reassess passage” until the situation normalizes, according to a circular, seen by Bloomberg that its shipping ministry sent to vessel owners. It advised waiting in nearby safe ports.

Naval forces in the area warned that ships, especially U.S.-linked ones, could be at heightened risk. Shipping giant A.P. Moller - Maersk A/S said it continues to transit Hormuz but is ready to re-evaluate its position based on the information available.  

The actions of the maritime industry — and its risk tolerance — will be a critical detail in the wake of the strikes because of Iran’s proximity to the Strait of Hormuz, a conduit for a fifth of the world’s oil and an unavoidable searoute into the Persian Gulf.

Athens’ warning is the latest sign of pressure on shipping markets as attacks on Iran escalate. Tanker earnings already soared by almost 90% since Israel first started conducting airstrikes on June 13. As one of the world’s largest shipowning nations, advice to Greece’s vessel owners would have a major impact on commodity transportation markets, especially oil. 

There’s every chance shipowners will ignore the advice because the Persian Gulf is too-important a region for them to avoid and rates can always rise to compensate for the risk of sailing in the region. Operators that do decide to transit Hormuz should adopt the highest security level available and maintain the maximum possible distance from Iranian waters, Greece’s ministry added.

In Sunday’s notice, the Greek ministry cited concern around a possible closure of Hormuz as a reason behind its message. 

Officials at three Greek tanker companies said they were still assessing the situation. One did indicate he might still allow his tankers to enter the region, while another said their ships would likely stay away.

Greek government spokesman Pavlos Marinakis said in a statement that the government, via the shipping ministry, advised Greek-flagged and Greek-owned ships in the area of the Strait of Hormuz to go to safe port until the situation normalizes. 

Bigger Risk

Naval groups are also warning of greater risk. 

On Sunday, the Joint Maritime Information Center, a liaison between navies and merchant shipping in the region, said that the Washington’s airstrikes mean U.S.-linked ships sailing through the Red Sea and Gulf of Aden face a high risk of attack. 

Yemen’s Houthi rebel group issued fresh threats against American commercial and naval ships earlier in the day. There had been a ceasefire between the U.S. and the Houthis in early May, geared toward limiting the group’s attacks on the U.S. navy. U.S.-linked ships should consider re-routing, the JMIC said in its update.

Still, it said some U.S.-associated vessels have successfully transited the Strait of Hormuz, “which is a positive sign for the immediate future.”

Separately, the European Union’s naval force in the region raised its threat assessment for U.S.-linked vessels as a result of the strikes. It now sees a severe threat to ships linked to the U.S. and Israel and a low risk for all other ships. 

“This does not exclude the possibility of all merchant vessels being targeted in the future,” it said in an update published by France’s MICA Center, which helps co-ordinate global maritime security.