[3] Subsequently, in 2019, satellite imagery of a modified Romeo-class submarine of about 3,000 tons displacement was shown to be under construction at Sinpo South shipyard.

[6] Kim Jong-un visited the site of construction, deemed the Pongdae submarine factory in 2019, and declared that a "new era" for the Korean People's Navy was arriving within a span of "five to ten years".

[1] Prior to the formal ceremony, the NIS noted that Russia proposed a joint naval exercise with North Korea and China in late July 2023.

[6] The naming and launching ceremony of the submarine occurred at Sinpo shipyard on 6 September 2023, subsequently announced two days later on North Korean state media.

James Martin Center associate Dave Schmerler observed from the state media photos that the submarine has four large and six small missile hatches, the large ones capable of launching medium SLBMs like the Pukguksong-3[1] capable of striking short-ranged targets in Japan and South Korea.

[14] In an interview by the Joint Chiefs of Staff of South Korea, one official raised question about the sub's capabilities, and that additional monitoring in coordination with the United States will continue in order to respond to provocations.