Chilean Navy Diesel-Electric Attack Submarine Appears In San Diego (Updated)

Working with foreign diesel-electric submarines provides valuable training to the US Navy, which only operates nuclear-powered types.

byJoseph Trevithick|
South America photo


A publicly accessible webcam shows what appears to be a Chilean Navy Scorpene class submarine sailing into the Port of San Diego in southern California earlier today. Though we don't know for sure what the purpose of its visit is, the U.S. Navy's Pacific Fleet has engaged with Latin American navies in the past as part of a program that offers valuable opportunities to work with, and train against, advanced diesel-electric submarines. Since 1990, the U.S. Navy has only operated nuclear-powered submarines.

The submarine first appeared on the feed from San Diego Web Cam at around 3:30 PM local time. At multiple points in the stream, the Chilean national flag is seen flying atop the boat's sail. At present, the Chilean Navy operates two Franco-Spanish Scorpene class submarines and a pair of German-made Type 209/1400-Ls, known in the country as the Thomson class. The Scorpenes are easy to separate from the Thomsons, with the former type having dive planes on the sail, while the latter does not.

San Diego Web Cam capture

The Chilean Scorpenes, the first of which, the O'Higgins, entered service in 2005, are fairly modern diesel-electric attack submarines. Among other things, they feature air-independent propulsion (AIP) systems, which allow them to dive for days at a time while remaining very quiet and, and as a result, difficult to detect and track. AIP-equipped diesel submarines are now proliferating around the globe and are considered major threat. Each one of the Scorpene class has six torpedo tubes that can be used to fire Black Shark heavyweight torpedoes or Exocet anti-ship cruise missiles.

The reason for this submarine's visit to San Diego is unclear and we have already reached out to U.S. Third Fleet, which is headquartered there, for more information. In 2001, the U.S. Navy did begin working with boats from various Latin American nations as part of the Diesel-Electric Submarine Initiative (DESI), a combined training program that units on the West and East Coasts take part in. Ostensibly, these combined training events are meant to give all of the participants opportunities to practice various core skills sets relating to submarine and anti-submarine warfare (ASW) operations, as well as help broaden ties, in general, between the U.S. military and its partners in the Southern Hemisphere.

The Chilean Navy's Scorpene class submarine Carrera., SSBN via Wikimedia

However, since the U.S. Navy does not have any diesel-electric boats of its own, DESI has also provided particularly valuable opportunities over the years for it to train against these kinds of submarines, which have distinct operational characteristics and signatures from nuclear-powered ones. "During these visits, we are able to simulate a variety of wartime scenarios against diesel submarines which adds an additional degree of difficulty and reality to fleet ASW, as diesel submarines have proven to be quiet and elusive," Navy Lieutenant Alexander Papadakos, a member of Submarine Squadron 11, said during a DESI engagement with the Chilean Navy's Thomson class submarine Simpson, in 2018.

The Chilean Navy's Thomson class submarine Simpson., DOD

The U.S. Navy has sought out these kinds of opportunities in different ways since 1990, when it decommissioned the Barbel class USS Blueback, its last diesel-electric attack submarine. Blueback, one of just three Barbels the Navy acquired, had served for a time at the end of its career as an aggressor due to its unique characteristics among the rest of the service's submarine fleet. 

In the mid-2000s, the Navy then leased Sweden’s AIP-equipped HSwMS Gotland to serve as a diesel-electric aggressor. That period highlighted the value of being able to train against these kinds of submarines, with Gotland famously managing to sneak right into the middle of an aircraft carrier strike groups during exercises, as well as scoring simulated kills against various surface ships and other submarines during training engagements. 

The Navy has acquired at least two large-scale training targets designed to mimic diesel-electric submarines in the past two decades, as well. The service also operated the specialized research and development submarine USS Dolphin until 2007, which was its last commissioned diesel-electric boat of any kind.

More recently, in 2019, the service stood up a new dedicated submarine aggressor squadron, or AGGRON, to help in training submarine and anti-submarine forces. However, as it exists now, this unit's primary job is schooling Navy personnel in enemy tactics, techniques, and procedures, and helping submarines acting as the "opposing force," or OPFOR, to better represent potential threats. At least as of last year, it has no submarines permanently assigned to it and the Navy still has no plans to acquire its own diesel-electric types, which could add greater realism to exercises.

In the meantime, combined training programs, such as DESI, remain the most readily available ways for Navy submarine and anti-submarine forces to train against these threats.

So, while we don't know why exactly this Chilean Scorpene class boat is in San Diego, it is very likely there to, at least in part, provide very useful training for Navy personnel against a type of submarine they might not otherwise encounter on a routine basis during training.

UPDATE: 7/2/2021 —

The Chilean Navy has now officially confirmed the arrival of one of its Scorpene class submarines at Naval Base Point Loma in San Diego. A Spanish-language Tweet from that service simply says that it is there "to participate in an international operation with the @USNavy."

However, after our initial story was published, a reader also alerted us to a story in the Spanish-language defense and security magazine Infodefensa that said the Chilean Navy's Scorpene class submarine O'Higgins had left that service's base in Talcahuano in early June and that it was heading to the United States for exercises over the next five months.

"For more than five months it [the O'Higgins] will be deployed to operate with the most modern Navy in the world and even carry out submarine rescue operations," Rear Admiral Juan Pablo Zúñiga Alvayay, the head of the Chilean Navy's submarine force, was quoted as saying that story. "For this, a crew of more than 40 men, and with an average age of 32 years, will represent us. We wish them success, a good hunt, and a safe return home."

Infodefensa does not specifically mention the U.S. Navy's DESI program, but how Rear Admiral Zúñiga described the nature of the O'Higgins' current deployment, especially plans to conduct submarine rescue training, is well in line with previous Chilean Navy participation in that initiative.

"The highlight of the DESI deployment is CHILEMAR VIII, a submarine search and rescue exercise that will take place in August," the U.S. Navy news item regarding the arrival of the Chilean Navy's Thomson class submarine Simpson in San Diego in 2018 said. "Chile remains the only South American submarine-operating country to conduct frequent live submarine rescue exercises with U.S. Navy rescue assets at Undersea Rescue Command."

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