North Korea appears to have resumed work on a warship that has been under development for the last decade, according to NK Pro analysis of satellite imagery, following the long-awaited deployment of its sister ship in August.

The relocation of the roughly 250-foot (77 meter) vessel to a drydock in the northeast city of Rason may be to equip new weapons systems in preparation for its entering service, one expert said, as leader Kim Jong Un pushes to upgrade his naval fleet.

The ship, referred to by experts as a Tuman-class corvette, was moved to the drydock at the Rajin Shipyard between Nov. 21 and 22, Planet Labs imagery shows, where it remained as of Nov. 28.

It had been moored elsewhere at the shipyard for most of the last decade, but it was previously inside the drydock undergoing work for over 10 months between April 2022 and Feb. 2023. 

Imagery shows the ship was also in the drydock for over three months in mid-2021 and received a major overhaul while there in late 2017 to install weapons in place of a helicopter pad.

It has appeared in an advanced stage of development since those changes, but it’s unclear when it will be deployed. 

North Korea officially unveiled its first Amnok-class corvette in August, calling it Patrol Boat No. 661. It has been spotted in satellite imagery at various naval bases on the east coast including at Mayang Island, Rakwon and Munchon since then.

A Korean People’s Army (KPA) spokesperson said in August the military was also “examining an operation plan” to deter U.S. reconnaissance flights off the east coast by “constantly deploying a ship loaded with new-type anti-aircraft missiles.”

Tarao Goo, an analyst with the Oryx and Deep Dive military blogs, told NK Pro that the KPA may equip the Tuman-class ship at the Rason drydock “with a new main gun” or a surface-to-air missile (SAM) system “similar to the 9K330 ‘Tor’ that North Korea unveiled in 2020.”

He added, however, that such missiles “would not be able to reach high-altitude surveillance aircraft” and that “North Korea has no warships large enough to carry advanced radar, not even the Tuman.”

Tianran Xu, an analyst with Open Nuclear Network, told NK Pro in August that the Amnok-class corvette — the same size as the Tuman — was unlikely to be able to handle the installation of a heavy long-range surveillance radar and fire control radar required to use a modern SAM system, like the truck-mounted system seen at recent DPRK military parades.

Goo said that like the Amnok-class, the Tuman-class corvette could be fitted with long-range cruise missiles that Pyongyang claims carry nuclear warheads, and that it could serve to generally patrol the east coast in concert with the Amnok if deployed. 

North Korea has also been developing one each of the Tuman and Amnok-class ships at Nampho on the west coast, with the one Goo has identified as the Tuman-class appearing to actively move between there and a naval base at nearby Pipha in the past year.

State media prominently covered DPRK leader Kim Jong Un’s high-profile inspection of Patrol Boat No. 661 in August, but it is unclear if he will put the spotlight on additional ship launches or new operations, or if they will quietly enter service. 

The corvette development comes as Kim has promised a major naval revival this year, though experts have warned the process will be long and costly. 

Kim visited KPA Navy headquarters in August where he inspected large engines for naval ships and christened a remodeled ballistic missile submarine in September. 

The DPRK leader also revealed active development of an “underwater nuclear attack drone” this past spring, and ordered the construction of a nuclear-powered submarine and production of sea-launched intercontinental ballistic missiles in Jan. 2021. 

Edited by Bryan Betts

Update on Dec. 11, 2023: The ship left the drydock and returned to its typical mooring spot at the shipyard to the north between Nov. 30 and Dec. 3. It also appeared to be sailing away from the bay on the morning of Dec. 5, possibly as part of trials, but was moored at the Rajin shipyard again from Dec. 7 to 9.