Greece’s Ministry of Shipping has advised the country’s shipowners to reconsider transiting through the Strait of Hormuz following U.S. airstrikes on Iran.

According to a report by Bloomberg, ships planning to navigate the narrow passage of the Persian Gulf should “reassess their transit through the Strait of Hormuz” until the situation stabilizes, the ministry said in a circular sent to shipowners.

Should vessels choose to proceed through the strait, shipowners are urged to adopt the highest available security protocols and maintain the maximum possible distance from Iranian territorial waters.

Freight rates had already increased last week amid rising tensions in the Middle East. Qatar has instructed LNG tankers to wait outside the Strait of Hormuz until they are ready to load. The Greek ministry cited growing concerns over a potential closure of the strait as the reason for its warning.

Separately, the European Union’s naval force operating in the region has raised its threat assessment for vessels linked to the U.S., in response to the airstrikes. The force now views U.S. and Israeli-affiliated ships as facing a serious threat, while assessing a low risk for all other vessels.