June 28, 2017 · Shāyú SCS Istina Eminent Shadow

Eminent Shadow Underway in the SCS

As tensions in the Spratly Islands continue to intensify, we are observing a marked increase micronaval activity in the region. Operation Eminent Shadow commenced on 1 April 2017 to provide persistent monitoring of naval activities in the South China Sea.


  • We reported in March of this year that China's Shāyú-class microsubmarine had completed sea trials and officially joined the PLAN, and that as many as a dozen were observed deploying from Yulin Naval Base on Hainan Island.
  • Following that report, on or about 1 April 2017, six 5-vessel Strikepods were airlifted to the region and deployed to areas near Fiery Cross, Subi, and Mischief Reefs.
  • In order to preserve OPSEC, Strikepods were ordered to maintain strict radio silence, transmitting only in the event of incapacitation, capture, or imminent threat to U.S. assets.
  • On 15 June 2017, Strikepods (Delta) 1-3 were ordered to surface for manual data transfer and immediate redeployment. They provided the following intelligence:

Strikepods were on station for approximately 48 hours when contact was made with twelve Shāyú-class submarines.

  • Four Shāyús patrolled the waters off each reef, orbiting in a roughly equidistant formation.

  • The Shāyú, like the North Korean Gwisin, appears to have limited network capability, operating as a lone actor with only occasional undersea communication and no observed collaboration with other vessels.

  • The Shāyús surfaced at regular, staggered intervals to transmit data and to receive tasking. Encrypted signals are still being analyzed by Strikepod Command.

  • On two occasions, Shāyús appeared to detect a nearby Strikepod, breaking from their established patrol pattern, accelerating, and passing within 10 meters. The vessels exhibited a high degree of manueverability and rate of acceleration.

  • At one point, Strikepod Delta-2 was able to observe a Shāyú tracking a Malaysian Scorpène-class submarine for approximately five days before it was forced to surface due to mechanical trouble. Rather than break off contact to indicate its position, the Shāyú periodically released microbuoys that rose to the surface to act as beacons for PLAN surface vessels. In addition to the buoys, the Shāyú also emitted an ultra high frequency signal via its active sonar, presumably to alert nearby PLAN submarines. Delta-2 alerted nearby Strikepods, who then began a wide-area search, but no PLAN submarines were detected.

Strikepods also detected the presence of several Russian vessels, including an Akula-class submarine, and eight Istina-class microsubmarines.

  • The Istinas were launched and recovered from the Akula via torpedo tube. Recovery via torpedo tube was achieved using an ROV system similar to the Saab SUBROV.

  • Like the Shāyú, the Istina appears to have limited network capability, though Strikepods did detect underwater communications between the Istinas, the Akula, and the ROV, suggesting a growing sophistication in Russian undersea communication.

  • On three separate occasions, Istinas made high speed passes in close proximity to Strikepods, suggesting (1) that the Russians were aware of our presence, and (2) that they wanted us to know. Analysis of AI data streams suggests that the Istinas were not deemed to pose a threat, however each Strikepod assumed a precautionary defensive formation in response.

Strikepods were redeployed on 20 June and will remain on station with standing orders to maintain radio silence. Strikepods (Delta) 4-6 are scheduled to surface between 28 June and 5 July for data transfer.

Strikepod Command


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