The challenge of mini-subs
The US Navy is more accustomed to tracking large, Soviet-era nuclear-class submarines — something Iran knows well, adds Commander Harmer. “Looking for small subs in shallow water is much more difficult, because the acoustics are so much more difficult — smaller makes less noise.”
As a result, he adds, the Iranian military-industrial complex “has prioritized these mini-subs — and have gone into overdrive building them.” Mini-submarines are generally considered any submarine vessel under 500 tons and roughly 100 feet long or less.
Five years ago, the Iranian military had “no mini-subs,” says Harmer, senior naval analyst at the Institute for the Study of War in Washington. Now they have 19 in service, and are building an average of four per year — a “strategically significant” force, he adds.
While the diesel-electric powered Iranian mini-submarines have limited range, they have torpedo tubes and can quickly lay mines, which is their most troublesome feature, according to US military officials.
Iran also has “significant special operations capability,” including “extensively” trained frogmen, says Harmer. However, at a tactical level, the most likely use of Iranian frogmen would be against civilian targets such as oil tankers and other international commercial maritime traffic, he adds.