On a warm spring night in Athens, just before midnight, a senior executive at a Greek shipping company noticed an alarming email in his personal inbox. The message, which had also been sent to his business email, warned that one of the company’s vessels, currently navigating the Red Sea, was at risk of being attacked by Yemen’s Iranian-backed Houthi militia.
The ship had reportedly violated a transit ban imposed by the Houthis by docking at an Israeli port, and was now a target. “The Yemeni Armed Forces will directly target the vessel in any area they deem appropriate,” read the email, which was written in English and reviewed by Reuters. “You bear the responsibility and consequences of including the vessel in the ban list,” it continued, signed by the Humanitarian Operations Coordination Center (HOCC)—a Yemen-based body established in February to mediate between Houthi forces and commercial shipping operators.
Since November, the Houthis have launched almost 100 attacks on ships passing through the Red Sea, in solidarity with Palestinians amid Israel’s ongoing conflict in Gaza. These attacks have sunk two vessels, seized another, and resulted in the deaths of at least four seafarers.
The warning email, received at the end of May, threatened “sanctions” on the entire shipping company’s fleet if they continued violating the imposed ban by entering Israeli ports. For safety reasons, the executive and the company remained anonymous.
This email was just the first of more than a dozen increasingly threatening messages sent to at least six Greek shipping companies since May, as confirmed by multiple industry sources. The growing geopolitical tension in the Middle East has caused the Houthis to expand their focus, targeting Greek merchant ships that have little or no direct connection to Israel.
One of these threatening emails, sent in June, came from a Yemeni government web domain. It stated: “Your ships breached the decision of Yemen Armed Forces,” and warned that “punishments will be imposed on all vessels of your company… Best Regards, Yemen Navy.”
Since last year, the Houthis have been launching missiles, armed drones, and boats packed with explosives at commercial vessels tied to Israeli, U.S., and UK interests. This email campaign, not previously reported, indicates a significant escalation in the scope of threats, now directed at entire shipping fleets.
Yemen, which controls a strategic chokepoint at the entrance to the Red Sea, has been locked in civil war for years. In 2014, the Houthis seized control of the capital, Sanaa, ousting the internationally recognized government. In January, the United States reclassified the Houthis as a terrorist organization.
When contacted by Reuters, Houthi officials refused to confirm whether they had sent the threatening emails, citing that it was classified military information. Reuters could not establish if other foreign shipping companies had also received similar emails.
Greek-owned ships, which constitute one of the largest merchant fleets globally, have been particularly affected. According to data from Lloyd’s List Intelligence, these vessels accounted for nearly 30% of the attacks carried out by Houthi forces up until early September, though the data did not specify whether the ships had ties to Israel.
In one of the most notable incidents, the Houthis attacked the *Sounion* tanker in August, leaving it ablaze for weeks before it could be towed to a safer location. The ongoing attacks have forced many cargo ships to opt for longer routes around Africa, avoiding the Suez Canal. Traffic through the canal dropped from about 2,000 transits per month before November 2023 to approximately 800 in August, according to Lloyd’s List Intelligence.
Tensions in the Middle East surged even higher when Iran retaliated against Israel by launching over 180 missiles on Tuesday. This response came after Israeli forces killed several militant leaders in Lebanon, including Hezbollah leader Sayyed Hassan Nasrallah.
In early September, the European Union’s naval force, Aspides, held a closed-door meeting with shipping companies, revealing that the Houthis had shifted their tactics. Aspides confirmed that the expansion of threats to entire fleets marked the beginning of the “fourth phase” of the Houthis’ military campaign in the Red Sea. A document reviewed by Reuters urged ship owners to deactivate their Automatic Identification System (AIS) transponders, which transmit a ship’s position. Aspides stressed, “shut it off or be shot.” Data presented during the briefing indicated that the Houthis’ missile strikes had a 75% accuracy rate when ships had their AIS on, but only 4% of missiles hit their targets when AIS was off.
Rear Admiral Vasileios Gryparis, Aspides’ operational commander, confirmed awareness of the email threats. He urged caution in responding and advised shipping companies to consult security experts before sailing. “In particular, for the HOCC, the advice or guidance is not to respond to VHF calls and e-mails from the ‘Yemeni Navy’ or the ‘Humanitarian Operations Command Center’ (HOCC),” Gryparis added.
The Houthis’ email campaign began in February, initially targeting shipowners, insurance companies, and the main seafarers union through the Humanitarian Operations Coordination Center (HOCC). These early emails, reviewed by Reuters, informed the industry about the Houthis’ Red Sea travel ban on certain vessels but did not directly threaten imminent attacks. However, by May, the tone of the emails had escalated, becoming more menacing.
At least two Greek-operated shipping companies that received these threatening emails have since stopped passing through the Red Sea, according to sources who spoke to Reuters, but declined to name the companies for security reasons. Another shipping company that received a similar warning decided to end its business dealings with Israel to continue using the Red Sea route. “If safe transit through the Red Sea cannot be guaranteed, companies have a duty to act—even if that means delaying their delivery windows,” said Stephen Cotton, General Secretary of the International Transport Workers’ Federation. He emphasized that seafarers’ lives depend on these decisions.
The email threats have heightened concerns within the shipping industry. Insurance costs for Western shipowners have surged due to the Houthi attacks, and some insurers have suspended coverage altogether. Greece-based Conbulk Shipmanagement Corporation stopped Red Sea voyages after its vessel, *MV Groton*, was attacked twice in August. “No (Conbulk) vessel is trading in the Red Sea. It mainly has to do with crew safety. Once the crew is in danger, all the discussion stops,” said Conbulk CEO Dimitris Dalakouras at a shipping conference in London.
Similarly, German container shipping group Leonhardt & Blumberg’s managing director, Torben Kolln, stated that the Red Sea and the Gulf of Aden are now considered “no go” areas for their fleet.
Many companies are forced to continue using the Red Sea due to long-term contracts or the necessity of transporting goods through this critical route, which remains the fastest way to connect Europe and Asia. However, Chinese and Russian-owned vessels, which the Houthis do not associate with Israel, have been able to cross the Red Sea more freely, facing lower insurance costs. According to a Houthi message broadcast to ships in the Red Sea in September, the militia reassured non-Israeli-affiliated vessels that they were safe and encouraged them to keep their AIS devices on.
Despite these assurances, the shipping industry remains wary, with many companies prioritizing crew safety over profit. The threat of Houthi attacks has cast a shadow over one of the world’s busiest maritime trade routes, significantly impacting shipping operations.
