Why it is hard to prevent drone attacks at sea


An Iranian drone struck a ship in the Gulf of Oman this week. It is at least the second time Iran has used an armed drone to attack a ship, last year it attacked the Mercer Street in the Gulf of Oman and killed two crew members. Iranian drone attacks used against ships are very hard to prevent.  This is because there are a large number of ships and they are vulnerable to these kinds of attacks. They can’t easily be armed with air defenses and it’s unclear how they can detect and escape drone strikes by kamikaze-style drones. 

What we know about the November 15 attack is as follows. The US Central Command says that an Iranian Shahed-series UAV struck a civilian commercial tanker around ten in the evening on November 15. The drone was an Iranian-made UAV the US has concluded. It struck the Pacific Zircon ship. There was damage to the vessel, but no harm to the crew. The debris from the drone was recovered and this enabled analysis of what type of drone it was. The drone was flown form the IRGC’s regional commander center in Chabahar in southeastern Iran, a senior western official confirmed to BBC’s Nafiseh Kohnavard

This appears to be the types of kamikaze drones Iran has improved in the last few years. It may be a type similar to the Shahed 136 that Iran has exported to Russia, or another type of Iranian drone in the Shahed family of drones. The US has condemned the Iranian attack as “destabilizing.” The US points out that it has a number of ships in the region, as part of a multinational force. This force includes the British Royal Navy’s HMS Lancaster, 2 US naval vessels, including the USS The Sullivans guided missile destroyer and the patrol coastal ship USS Chinook. The name of the ship The Sullivans comes from the five Sullivan brothers who died on the USS Juneau in 1942. That is why it is “The” Sullivans, an unusual name for a ship. The US also has patrol aircraft and other assets in the region.  

The US recently interdicted a shipment of 70 tons of missile fuel that was being transported on a dhow to Yemen. It appears that shipment was from Iran to the Iran-backed Houthis. “This type of shipment and just the massive volume of explosive material is a serious concern because it is destabilizing,” Cmdr. Timothy Hawkins, a spokesperson for Navy’s Mideast-based 5th Fleet, told The Associated Press. “The unlawful transport of weapons from Iran to Yemen leads to instability and violence.” In that incident the US Coast Guard ship USCGC John Scheuerman and the guided-missile destroyer USS The Sullivans stopped the dhow on November 8.  

The US Navy and other navies in the Gulf don’t have enough ships to defend this whole area from drone attacks. For instance, in 2020, as many as 17,000 ships transit the Bab el-Mandeb straits between Yemen and Africa every year; and 42,000 ships pass through the Strait of Hormuz annually. A total of 30,000 ships cross the Gulf of Aden every year, most heading to the Suez Canal. The volumes are huge. The UAE port of Fujairah on the Gulf of Oman handles some 60 million tonnes of cargo a year according to the website DFreight and some 4,000 vessels are hosted at the port in a year; with a total of 14,000 anchored off the coast annually. The overall sea area within the range of Iranian drones in this region could be some 1.7 million square kilometers, if Iran can also launch its Shaheds from Yemen itself. It doesn’t seem possible or plausible that so many square kilometers can be defended, nor that tens of thousands of ships can be defended. 

However in the case of Iran the country likely only threatens some of the ships that transit this area. The cases of the Mercer Street, Hyperion Ray, Helios Ray, Lori and CSAV Tyndall, ships that were affected by incidents in the last year and a half, most reports alleged that these ships were thought to be linked to Israeli owners and thus Iran’s targeting was linked to Iran seeking to strike at Israel by striking commercial ships, rather than military targets. Iran and its proxies have also targeted other vessels; in May and June 2020 they struck a number of vessels off the coast of the UAE using mines. The May 2019 incident targeted a ship flying a UAE flag, one ship flaying a Norwegian flag and two Saudi-flagged vessels. It’s important to note that the flag a ship carries and its ownership may always be complex, such that ships flagged in one country may be owned by a company in another, and managed by a company in a third country. Iran has also targeted US naval ships, and it has targeted UK and Greek-owned ships. In June 2019 two ships, one operated by a Japanese company and the other by a Norwegian company, were targeted by mines. Other ships have been affected by Iran’s activity, such as a ship called “Gulf Sky” and a Vietnamese oil tanker and a South Korean tanker.  

This means that Iran’s long arm, including using fast boats and other types of ships, as well as drones, can threaten a huge region and a lot of ships. Even if one were to reduce the number of possible targets by selecting out the ships flagged and owned by countries unlikely to be threatened; there are still thousands of potential targets. One can’t put air defense systems on these ships and arming commercial ships in general is frowned upon internationally. In the 1980s the US engaged in Operation Earnest Will to protect ships in the Persian Gulf. This involving re-flagging Kuwaiti ships. Iran and Iraq both attacked numerous ships beginning in 1984 when Iraq began striking at ships in what became known as the “Tanker war.” Therefore the drone attacks today are not exactly a new type of policy by Iran; and it’s not a unique policy that Iran invented. However, drones pose a new type of threat. 

Drones can be used on one-way missions, and these types of drones are usually called kamikaze drones as well as “loitering munitions.” It’s unclear how Iran has been able to program the drones to carry out these missions. A moving ship is difficult to strike with a drone that relies on coordinates or way points during its mission. If it has to fly toward a moving ship this means there may be a “man in the loop” or some other way for the drone or another device to track the ship. It’s also not clear if Iran is able to guide the drone to strike a certain part of the ship. In July 2021 the Iranian drone hit the bridge of the ship, killing two crew. This time the drone didn’t harm anyone. Obviously if drones are striking tankers they could cause a huge environmental incident. They could also be used to disable a ship by striking at the rudder area. This is a deadly weapon and many questions about its guidance and the munitions it carries still need to be answered. This is why the drones are hard to deal with as a threat. It’s not always clear where the drones might be flown from; either Yemen or Iran; and after they are detected it’s hard to shoot them down or jam them and push them off course. Drones are usually slow so if they are detected they can be shot down by armed planes or even helicopters, but that would require the US or other countries to have planes on stand by to intercept the drones. Advanced warning might be more helpful. It’s also unclear if countries are willing to go after those launching the drones. The drone threat is a new type of threat at sea and Iran may now want to launch more drone attacks on ships.  

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