Iran's threat to Gulf undersea cables and the network carrying nearly all internation
Iran's threat to Gulf undersea cables and the network carrying nearly all international web traffic
M.U.H
24/10/202616
Iran's threat to cut the undersea cables beneath the Gulf would barely dent the world's internet, but it could slow the region's access to the web, online payments and cloud services for weeks because a broken cable is hard to repair in a war zone.
Two senior Iranian security officials told Reuters on Friday that Tehran has drawn up detailed plans to target the cables if the US and Israel attack Iran again. One of them said Iran would try to stop repairs to prolong the disruption.
Under the Gulf
Undersea cables carry around 99% of international internet traffic, according to the International Telecommunication Union (ITU), the United Nations agency for digital technologies. There are hundreds of them, most not much wider than a common garden hose. Inside each cable are hair-thin glass fibres that carry the data.
Some undersea cables carry electricity between countries as well.
Several fibre-optic cables cross the seabed of the Strait of Hormuz, which separates Iran and Oman and links the Gulf to the Gulf of Oman and the Arabian Sea. They include Asia-Africa-Europe 1, which connects Southeast Asia to Europe via Egypt and comes ashore in the UAE, Oman, Qatar and Saudi Arabia; FALCON, which connects India and Sri Lanka to the Gulf states, Sudan and Egypt; and Gulf Bridge International, which links all the Gulf countries, including Iran.
TeleGeography, a telecommunications research firm, says the share of international bandwidth passing through the strait was less than 1%. Capacity routed through the Red Sea, which carries data between Europe, East Africa and Asia, accounts for about 3% of global international demand, it says.
Reuters reported that the Red Sea could offer Iran a bigger target than Hormuz, particularly with help from the allied Houthis in Yemen, though Tehran has made no public statement about targeting cables there.
India had about 17 submarine cables coming ashore at 14 cable landing stations, with the largest concentration in Mumbai and Chennai, the Telecom Regulatory Authority of India (Trai) said in 2022. A landing station is the building near the coast where an undersea cable joins the networks on land, often "a sort of concrete box somewhere on a beach", said Katja Bego, a senior research fellow at Chatham House, a London think tank, and author of a new book on subsea cables, speaking on a Reuters podcast.
What a cut would do
About 150 to 200 cable faults are recorded worldwide each year, and 70% to 80% are caused by accidents, mostly fishing gear and ship anchors, according to the International Cable Protection Committee (ICPC), an industry body. Operators build spare routes into busy corridors, and in 2024, the Red Sea had 14 cables in service with six more planned, the Associated Press reported.
Bego said that after cable breaks in the Baltic Sea in recent years, "internet users didn't notice much, because traffic could be rerouted quite seamlessly to other cables". Land connections also offer alternative routes, and Gulf states and US technology companies are investing in more infrastructure to make their networks more resilient, Reuters reported.
Analysts told Reuters that several cuts at once could slow internet services and disrupt financial transactions, e-commerce and cloud computing, with the effect depending on how operators rerouted traffic and how much spare capacity other connections had. Satellites are not substitutes, since they carry far less traffic, cost more and also depend on networks on the ground.
Why repairs are the hard part
Engineers on shore find a break by sending pulses of light down the fibres and timing how long the reflections take to come back. A repair ship then hauls the cable to the surface, cuts out the damaged stretch and splices in a new one, fusing the glass strands with an electric arc and sealing the joint before lowering the cable back to the seabed.
In water shallower than 1,500 metres, a repair generally takes one to three days once the ship is on site, Rear Admiral Mike Brookes, who commands the US Navy's Office of Naval Intelligence, said in a written answer to the US-China Economic and Security Review Commission, a body set up by the US Congress.
The average repair in 2024 took 51 days, he wrote, with the wait for maritime work permits, the availability of ships and the weather among the factors that set the time.
About 65 cable ships worldwide work on communication cables, and about 20 of them are mainly assigned to repairs. If more than one cable breaks within one maintenance zone at once, repairs are prioritised "largely by the impact on traffic and network redundancy, and the availability of maritime work permit approvals", he wrote.
Bego, describing a possible clash with Russia in which many European cables are cut at once, said the question then becomes "which cables do you repair first?"
Experts say that restoring connections in wartime could be difficult, with higher insurance costs and delays in obtaining permits to enter territorial waters adding to the problem. Owners of repair ships and their insurers also weigh the risk of fighting and mines, and once a conflict ends, operators have to survey the seabed again to avoid wrecks.
In early 2024, three Red Sea cables were cut after a cargo ship hit by the Houthis drifted and dragged its anchor across them. Yemen's internationally recognised government had alleged that February that the Houthis planned to attack the cables. The Houthis denied targeting them and later warned that any cable-laying ship entering Yemeni waters needed a permit from them.
The law
Governments agreed to protect undersea cables in the Convention for the Protection of Submarine Telegraph Cables, signed in Paris in 1884, which made it a punishable offence to break or injure a cable wilfully or through culpable negligence.
Persia, as Iran was then known, was among the countries party to it. The treaty applies only outside territorial waters, and its Article XV, in the English text Britain adopted in 1885, says: "It is understood that the stipulations of the present Convention do not in any way restrict the freedom of action of belligerents." Britain's first act of war in 1914 was to cut Germany's undersea cables in the North Sea, and Germany was unable to repair them for the rest of the war, Bego said on the podcast.
The UN Convention on the Law of the Sea (Unclos), adopted in 1982, carried the 1884 rule forward. Article 113 of the convention requires every state to make it a punishable offence for ships flying its flag or people under its jurisdiction to break or injure a cable "beneath the high seas done wilfully or through culpable negligence". Article 58 extends that rule to each country's exclusive economic zone, a band of sea up to 200 nautical miles from its coast. Closer to shore, in a territorial sea of up to 12 nautical miles (about 22km), the coastal state is sovereign over the water and the seabed, under Articles 2 and 3.
