This week saw new satellite images from commercial satellites released to the public. Analysts quickly determined that work was continuing on upgrading and/or maintaining the network of secret sites dotted across the country. Along with these new developments, analysis group 38North also reported that the Sohae satellite launching ground, situated in the north eastern region of the country, has continued to show "low level activity".
Sohae was the site of the most significant satellite launch by the DPRK in 2016. Kwangmyongsong-4 launched into low earth orbit onboard the Unha-3 satellite launch vehicle. The launch was condemned nothing more than a test of missile technology and capability, however the launch cemented Sohae as one of the most capable launch sites in the country. 38North reported that no dismantling of the engine test stand or any other facilities on the base had been seen since early August 2018.
Whilst it was never in any real doubt that a network of camouflaged missile bases existed in the country, these recent images have brought the topic to the forefront of negotiations with some calling for Pyongyang to disclose the location of these bases as part of any denuclearisation deal. It is worth noting however, that missile bases may not as vital to the national nuclear program as you would expect. Some of the most missiles, most notably the Hwasong 14 and 15 which qualify as Inter-Continental Ballistic Missiles, may not even require fixed launch sites and may be capable of launch from the TELs (Transporter Erector Launchers) seen in their launch footage. Smaller missiles have also been seen launching from mobile vehicles making fixed launch sites potentially redundant to the nuclear force during wartime. The Hwasong 14 and 15 have not been seen launching from their TELs, instead were launched from fixed sites during their tests in 2017.
Pyongyang is, understandably, unwilling to divulge the information regarding the sites of the military bases, launch sites and other underground facilities which many suspect house the bulk of the nuclear and missile programs. The government likely fear that such information could easily become a target list should tensions rise in the future resulting in US strikes on military infrastructure.
While many analysts and US officials discuss the implications of such a discovery in the DPRK, the other argument is that maintaining such sites is very logical on Pyongyang's part. No framework or agreement has been signed regarding the closure of nuclear or missiles sites, with the exception of the Tongchang-ri site. The shutting down of such sites would be a major concession which could give the DPRK leverage in ongoing negotiations, so closing them prematurely as a 'goodwill' gesture wouldn't make much sense politically. Also, closing down military bases which the government considers vital for national defence would be a risky move whilst there is still no sign of any solid peace regime being put in place on the peninsula. What is important to remember, is that there has been no concrete agreement signed between Pyongyang and Washington which stipulates that such sites must be dismantled, and so it should come as no surprise that North Korea is maintaining these missile launch sites to ensure they are able to operate at maximum capability in case talks break down, or until they can be used as concessions in the nuclear talks.
38North report on Sohae: https://www.38north.org/2018/11/sohae110818/