The decisive factor in any confrontation between the US and Iran in the Gulf is not the number of American warships deployed, but the geography of the theatre itself and the asymmetric capabilities Tehran has built to exploit it, according to bne IntelliNews military analysts Patricia Marins.

“The problem for President Trump is not the number of American ships sent to intimidate Iran,” Marins says. “The real issue is the theatre of operations itself, its geography, bathymetry, and the asymmetric force Iran has deliberately built to exploit them.”

The Persian Gulf is among the shallowest seas in the world, with an average depth of 35–50 metres and a maximum of about 120 metres near the Strait of Hormuz. Such shallow, saline and high-temperature waters complicate sonar operations and favour smaller, highly manoeuvrable platforms. Even in the deeper Gulf of Oman, waters along Iran’s coast average around 200 metres, where Tehran operates five to six larger submarines, including Russian-made Kilo and Fateh-class boats.

“A US Carrier Strike Group cannot operate inside these gulfs without extreme risk,” Marins argued. Even if positioned 1,500km offshore in the Arabian Sea, US vessels remain within range of Iranian missiles, submarines and drones. To project power effectively, American naval forces must pass through the narrow Strait of Hormuz — precisely where Iran has concentrated its asymmetric assets.

Central to that strategy is what Marins describes as Iran’s “Mosquito Fleet”: an estimated 1,500 fast attack craft, many under 10 tonnes and capable of speeds of 50–110 knots. Around 250–300 are armed with anti-ship missiles including the Nasr, Kowsar, Ghader and Zafar. Designed for swarm tactics and saturation strikes, these vessels are supported by catamarans equipped with vertical launch cells for air-defence systems with ranges exceeding 100km.

Iran’s undersea capabilities are equally tailored to littoral warfare. Of an estimated 28–30 submarines, roughly 20 are Ghadir-class midget submarines capable of laying mines, launching torpedoes and firing submerged anti-ship missiles.

“These 20+ mini-submarines turn the shallow waters into a lethal ambush zone,” Marins wrote, arguing that larger US submarines would struggle to manoeuvre in such constrained conditions.

Unmanned systems add another layer of complexity. Tehran has invested in unmanned underwater vehicles, including torpedo-shaped hybrid systems capable of loitering before striking slow-moving targets. It has also deployed explosive unmanned surface vessels and a growing fleet of UAVs, including the Shahed-136B with a reported range of up to 4,000km.

Taken together, Marins contends that the Gulf’s physical constraints and Iran’s asymmetric doctrine create a battlespace that limits the operational freedom traditionally enjoyed by US naval power.