The Ohio Class Guided Missile Submarine USS Georgia gave the Iranian Navy quite a start this week when it came to periscope depth and announced its presence in the vicinity of an exercise that Iran was conducting. In the exercise, Iran was testing a new model of submarine.

According to the unofficial State Iranian news outlet Tasnim News, the Iranian Navy was conducting a torpedo firing drill when it detected the presence of an unidentified submerged contact in the immediate area.

The Iranian Navy sent at least two Sea King Helicopters to investigate the contact and discovered the USS Georgia just below the surface with her periscope up.

https://twitter.com/Iran_Military/status/1349723249593122816

The story does not mention the new Iranian submarine that was tested in the exercise but it was likely the Iranian Navy’s new Fateh class diesel submarine. This small coastal patrol submarine is said to be home-manufactured by Iran. It is an upscaled version of a North Korean midget submarine which the Iranian Navy has some experience operating.

The Iranian exercise had begun on Wednesday and took place off the Makran coast in southeast Iran and in the northern area of the Indian Ocean.

The Georgia’s presence in the area was not accidental.

The Iranians did not detect the Georgia as much as she announced her presence by cruising so near the surface. A submarine’s deployed periscope is visible for many miles on radar as a moving contact and a surface search radar of decent quality would be able to detect it. That would cause quite a stir. Furthermore, as one would approach even the wake would be visible on radar.

The Georgia is an Ohio Class submarine. It was originally built to launch ballistic missiles with nuclear warheads.

The Ohio class submarines are among the most silent ever built by the U.S. Navy. They were part of our strategic deterrence during the Cold War.

In converting her over to a cruise missile submarine (SSGN) platform she was upgraded to feature state-of-the-art noise and vibration reduction technology.

The Iranian Navy is not known for having anything approaching a first-world anti-submarine capability. Thus, it is highly unlikely that it detected the Georgia until the submarine was ready to announce its presence.

The Georgia’s purpose in the area cannot be precisely known but the Ohio Class SSGN has a full suite of acoustic surveillance sensors that would have allowed her to monitor the exercise from some distance.

More importantly, her hydrophone arrays, which run nearly the length of her hull, would allow her to record the new Fateh submarine’s sound signature and that of its torpedo. The Georgia might have also been testing the range and response time of the Iranian Navy. Finally, and what is most probable, the Georgia’s purpose could have been to disrupt the exercise by approaching the test area. And detecting a U.S. submarine’s approach would certainly do that.

On a video of the contact an Iranian helicopter can be heard announcing, “Unknown submarine, unknown submarine, this is Iranian Navy Helicopter,” and trying to make contact with the sub without success.

The Georgia arrived in the region on or about December 21 as she transited the Strait of Hormuz on a western course and into the Persian Gulf. She was sailing on the surface.

However, the Iranian exercise described above took place in the Indian Ocean, which means that the Georgia, at some point, traveled east again undetected through the Strait of Hormuz. It is also quite possible that the Georgia had tracked the new Fateh subtype to its training area, quietly shadowing it the whole way.

This realization would have been especially galling to Iran since it believed that the Georgia was still in the Persian Gulf.

And that may have been the point too: Iran’s newest submarine silently tracked and surveilled to its training area by a nearly 40-year-old Ohio class submarine. To add insult to injury the U.S. submarine managed an undetected shallow water transit of the Persian Gulf which Iran claims as its territorial waters.