North Korea’s largest modern warship appeared to be sailing in the waters of Nampho Bay on the west coast around midday Thursday, according to NK Pro analysis of satellite imagery, possibly as part of a test involving missile launches and the DPRK leader.

The activity comes after leader Kim Jong Un said earlier this month that the No. 51 Choe Hyon destroyer will officially deploy in “mid-June.”

Kim made the comments while overseeing the 5,000-ton warship’s first reported navigation test outside the West Sea Barrage that protects Nampho Bay, sailing a “120-nautical-mile stretch of the West Sea.”

State media reported at the ship’s launch ceremony in April 2025 that it was assigned to the East Sea Fleet, suggesting it could sail around South Korea to the DPRK east coast next month — an event likely to put Seoul and Washington on high alert.

Planet Labs satellite imagery showed the destroyer in two locations on Thursday. In one image taken at 11:25 a.m. KST, the ship appeared missing from the dock at the Nampho Shipyard where it has been anchored most of last year. 

A ship matching its size (about 140 meters long) appeared at the same time sailing eastward away from the barrage and toward the shipyard. 

In another image taken at 12:02 p.m., the same ship appeared around 830 meters south of the shipyard.

Most previous state media reports on the ship’s preparations for deployment mentioned or showed weapons testing from inside Nampho Bay, including launches of cruise missiles and surface-to-air missiles (SAMs).

But there was no mention of weapons testing during the reported navigation test in the open ocean outside the bay earlier this month. 

South Korean military authorities have not announced the detection of any missile launches on Thursday. However, the Joint Chiefs of Staff typically alerts the public in real time only when North Korea launches ballistic missiles, not cruise missiles or SAMs.

It’s possible that DPRK state media will report on the warship’s activities as early as Friday morning, though the navy may have also entered a stage of more regular testing without Kim Jong Un on site as it nears deployment.

Meanwhile, North Korea has yet to finish a large new naval base north of Wonsan on the east coast that is slated to be the home of the new Choe Hyon-class destroyers. 

If the ship indeed sails from Nampho to the east coast next month, it may dock at the unfinished base or at other large but aging bases like those at Rakwon, Mayang or Orang.

Smaller corvettes finished in recent years are currently stationed at the Pipha naval base just outside Nampho on the west coast, as well as Kosong near the inter-Korean border and Mount Kumgang resort on the east coast.

Update on May 29 at 11 p.m. KST: The No. 51 destroyer again appeared missing from the Nampho Shipyard on Friday. It may have sailing or conducting tests in the Nampho Bay, as a ship matching its size appeared there (coordinates: 38.68293° N, 125.27388° E) in a Planet Labs image taken at 11:28 a.m. A large land target on nearby Sangchuira Island also exhibited signs of being struck with projectiles between May 24 and 29, possibly as a result of missile test from launch vehicles on the west coast on May 26, or unreported and unconfirmed missile tests from the warship.  

Edited by Bryan Betts

Correction on May 30 at 1:05 a.m. KST: The headline incorrectly said Tuesday instead of Thursday