North Korea building new submarine pens (probably)

The new construction (probably submarine pens) is less than 3km from Mayang Do Primary Naval Base on the east coast (see See Naval Bases and Fleet HQs map above) of North Korea. Sinpo "SSBs" might operate out of Sagin Ni (under West Sea Fleet Command) and Sinpo/Mayang Do (under East Sea Fleet Command).  (Map courtesy US Defense Intelligence Agency (DIA)) For Sinpo class "SSBs" (see diagram below) 

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For Background on Submarine Pens (WWII and Cold War) see the previous article of July 25, 2016.

IHS Jane’s, July 22, 2016, reports North Korea is constructing a concrete fortified structure near the port of Sinpo that looks like pens capable of covering conventionally powered ballistic missile submarines (SSBs). I would guess that UK and US naval intelligence have been doing the observing and analysis then feeding the following to Jane’s (the conduit to we the public).

The construction is 2.25 km south of Sinpo shipyard and close to the Mayang Do Primary Naval Base (see it marked on map above), on the east coast of North Korea.

Commercial satellite imagery shows construction began August 2009 - November 2012 with the harbour blocked off by a sea wall and filled in by November 2012. Visible dock excavations have been made and concrete pored for protective slab roofs. 

Two pens are approximately 150m long, 10m wide, and 14m apart. I would say these are large enough to take 5,000 – 6,000 tonne submarines that have beams less than 10m.

Satellite imagery from 8 May 2016 revealed construction on the pens had progressed to portions  being covered with earth. Construction was still ongoing on the front of both pens and a barge was tied to the seawall. The new pier, now 137m long and 13m wide, was nearing completion.

North Korea already has several submarine bunkers, at least some of which are capable of accommodating its obsolescent Romeo class SSKs.

This diagram of the Singpo clas SSB (at 68m long, 6.5m beam) is clearly small for the pens. Maybe 2 to 4 could be squeezed into the larger pen space of 137m long and 13m wide. H I Sutton of Covert Shores has produced excellent artwork, photos and description here depicting a North Korean "Gorae" Sinpo class SSB with two SLBMs mounted in the fin. 

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Pete