Arabian Sea's unique features offer advantages for key US submarines

The Arabian Sea's unique features make it an ideal operating environment for the US Navy's Ohio-class submarines as they expand operations in the Indian Ocean.

Russia's unprovoked invasion of Ukraine has caused many repercussions around the world, including soaring energy costs and increasing world famine, but it also indirectly strengthened the US military's ability to operate in the Indian Ocean.

North Atlantic Treaty Organisation (NATO) allies have ramped up patrols in waters normally handled by the US Navy, enabling the US to put a greater focus on the Indian Ocean.

The expected ascension of Sweden and Finland into NATO will also add their naval arsenals to the communal defence posture and lighten the US Navy's load in Europe.

In the Indian Ocean, the Arabian Sea is becoming a strategically important region, and its features are ideal for the US Navy's Ohio-class nuclear-powered submarines.

The Arabian Sea has two important branches. The first runs from the Gulf of Aden in the southwest and the Red Sea through the strait of Bab al-Mandeb. The second goes through the Gulf of Oman to the northwest, connecting with the Persian Gulf.

With an area of almost 3.8 million square kilometres and a maximum depth of 4,652 meters, the Arabian Sea provides an endless amount of safe patrolling areas and launch points for an Ohio-class submarine.

Its average depth of 2,734 metres also makes it deeper than the Persian Gulf, which itself is shallow in many places and generally seen as less suitable for large submarines.

The sea also has unusually deep water near bordering lands, except in the northeast, off Pakistan and India, and few islands exist in the area.

The Arabian Sea is also recognised as one of the world's warmest seas.

The Arabian Sea's depth-temperature profile has an effect on the travel of sound waves and the effectiveness of sonar, a common technique used to detect subsurface vessels.

For example, active sonar, which detects submarines by sending out a pulse a sound and listening for echoes, is less effective.

In the Sea's warm waters, the returning signal often gets lost.

The Ohio-class

Ohio-class submarines are the largest submarines ever built by the US Navy.

The class includes 14 ballistic missile submarines (SSBNs) and four cruise missile submarines (SSGNs).

"With a length of 560 feet [171 metres], a submerged displacement of 18,750 tons and a payload of 24 multiple-warhead, long-range Trident ballistic missiles, each of [the SSBNs] provides the Navy with an unparalleled combination of stealth, strategic capability and superior operating capability," according to General Dynamics, the company that built the submarines.

The Ohio-class SSBNs "may be the most destructive weapon system created by humankind," wrote Sebastien Roblin for the National Interest in 2021.

"Each of the 170-meter-long vessels can carry twenty-four Trident II submarine-launched ballistic missiles ... which can be fired from underwater to strike at targets more than seven thousand miles [11,265km] away depending on the load," he continued.

"As a Trident II reenters the atmosphere at speeds of up to Mach 24, it splits into up to eight independent reentry vehicles, each with a 100- or 475-kiloton nuclear warhead."

"In short, a full salvo from an Ohio-class submarine -- which can be launched in less than one minute -- could unleash up to 192 nuclear warheads."

For their part, the Ohio-class SSGNs can carry up to 154 Tomahawk cruise missiles, the equivalent of what is typically deployed in a surface battle group.

The Tomahawk cruise missiles themselves have a 1,000-mile [1,609km] range.

The SSGNs can also be configured host up to 66 special operations personnel, such as US Navy SEALs.

For many years, the Navy's Ohio-class submarines have traditionally operated in the Atlantic and Pacific oceans.

In December 2020, the USS Georgia became the first US nuclear submarine in eight years to cross the Strait of Hormuz, between the Persian Gulf and the Gulf of Oman -- on the surface, to maximise visibility and to convey US resolve. The USS Florida preceded it in 2012.

Just placing one Ohio-class submarine in the Arabian Sea would significantly enhance the US global posture and help achieve surprise in a conflict.

Growing threats

The US Navy's increased presence in the Arabian Sea comes amid its growing strategic importance.

It is the waterway that all Iranian ships must pass to reach world ports, and a key link in China's "string of pearls".

China's massive infrastructure drive to connect its mainland to the Horn of Africa via a network of military and commercial facilities in recent years has raised concerns.

Its sea lines run through major maritime choke points including Bab al-Mandeb Strait at the entrance to the Red Sea; the Strait of Malacca, between the Indian and Pacific oceans; the Strait of Hormuz, at the entrance to the Persian Gulf; and the Lombok Strait, between the islands of Bali and Indonesia.

Beijing's global infrastructure drive, known as the Belt and Road Initiative (BRI) or One Belt, One Road (OBOR), continues inland, reaching other parts of the Middle East, Central Asia and Africa.

China's ostensibly commercial projects serve a dual purpose, allowing for its rapidly growing military to expand its reach, warn critics.

Ohio-class SSGNs and their Tomahawk missiles could also play a major role in a potential conflict in the Arabian Sea and the surrounding region.

Iran has long threatened to close the Strait of Hormuz and attack maritime vessels in the event of war.

The destruction of critical infrastructure in the Zagros mountain range, especially of air defence systems, would allow forces opposed to the Iranian regime free rein over a key corridor that would enable aircraft and cruise missiles to hit vital targets.

The Zagros mountains, a southern extension of the Caucasus, run from southeastern Turkey through northeastern Iraq and roughly follow Iran's western border down south along the coast of the Persian Gulf up to Bandar Abbas on the Strait of Hormuz.

The range forms a natural barrier not only with the western border with Iraq but along Iran's southwestern border along the Persian Gulf.

Control of the mountains would allow for cruise missiles launched from submarines operating in the Gulf to penetrate Iranian territory with ease.