During a military parade on 8 February to mark the 75th anniversary of its armed forces, the DPRK showcased at least 12 Hwasong-17 intercontinental ballistic missiles (ICBMs) and 4 previously unseen, presumably solid-propellant ICBMs.
The presumably solid-propellant ICBMs are significantly longer than the large submarine-launched ballistic missiles (SLBMs) showcased by the DPRK in previous parades, indicating that the two ballistic missiles are based on different designs to best fit their respective requirements.
The unprecedented number of 16 very large transporter-erector-launchers (TELs) carrying those ICBMs suggests that the DPRK may have become less constrained by the sanctions-limited import of heavy-duty trucks, potentially allowing the DPRK's land-based ICBM force to expand rapidly.
It appears that the DPRK's solid-propellant ICBMs may have entered full development phase.
The Solid-Propellant ICBM
In comparison to previous military parades, the parade on 8 February put a strong focus on the intercontinental-range nuclear strike force: the parade only displayed a few conventional and short-range nuclear-capable weapon systems, but showcased an unprecedented number of 12 Hwasong-17 ICBMs. 
The only new items observed in the parade were the presumed solid-propellant ICBMs. Initial measurement shows that the launch canister of the new solid-propellant ICBM is approximately 26.5 m long and has a diameter of approximately 2.1 m (see Appendix). Accordingly, the missile itself would be approximately 2 m in diameter and 25 m in length.  While this newly showcased solid-propellant ICBM shares some visual similarities with the Soviet RS-12M (Figure 1), the DPRK model appears to be longer  and larger overall, allowing for a less sophisticated missile design and/or less compact nuclear warhead.
The solid-propellant ICBM showcased during the February 2023 parade is also significantly longer than the large solid-propellant submarine-launched ballistic missiles (SLBMs) displayed by the DPRK in previous parades. It may also be slightly thinner than the large, unnamed solid-propellant SLBM showcased during a parade in April 2022 and the solid-propellant motor tested on 15 December 2022 (Table 1). The clear difference in length and the possible difference in diameter indicate that the DPRK has not settled on one design for both land- and sea-based ICBMs.
The possibility that these newly showcased ICBMs were merely display models can not be completely ruled out at this time - the DPRK showcased two types of presumed solid-propellant ICBM models in 2017, neither of which have been seen since.  However, considering Kim Jong-un's order to develop land- and sea-based solid-propellant ICBMs  and the test fire of the large solid-propellant motor in December 2022, it appears that solid-propellant ICBMs may have entered full development phase.
Most ICBMs Ever
The appearance of at least 16 heavy transporter-erector-launchers (TELs) is unprecedented. In 2013, a UN Panel of Experts report documented the sale of 6 WS51200 heavy-duty trucks to the DPRK in 2010.  Those trucks have been used to carry the Hwasong-13 ICBMs and the Hwasong-14 ICBMs. They have also been heavily modified and extended (adding from 1 to 3 axles to the original 8-axle truck) to accommodate the larger ICBMs, namely the Hwasong-15 and Hwasong-17.
It remains uncertain how many WS51200 trucks and/or key subsystems have been acquired by the DPRK in total. For example, 8 similar heavy-duty trucks (4 Hwasong-15 TELs and 4 Hwasong-17 TELs) appeared in the 10 October 2020 parade,  surpassing the 6 previously documented by the UN Panel of Experts. The display of at least 16 large TELs (9 and 11 axles) in the 8 February 2023 parade indicates the DPRK might be able to build such TELs locally or has managed to procure key subsystems for local assembly. In either case, the DPRK seems to have become less constrained by the sanctions-limited supply of heavy-duty trucks, potentially allowing the land-based ICBM force to expand rapidly.
The primary reference used for the initial measurement of the presumed solid-propellant ICBMs showcased during the February 2023 parade is the distance between the outer edges of two grass lawns at the Kim Il-sung Square, which can be measured on high resolution satellite images such as Google Earth images (Figure 3). Accordingly, the diameter of the launch canister could also be estimated (Figure 4). ONN will conduct more refined measurements as further information is made available.
 The only confirmed successful test launch of the Hwasong-17 ICBM to date took place on 18 November 2022. See: Tianran Xu, Brief on DPRK ICBM launch on 18 November 2022 - Updates, 21 November 2022, Open Nuclear Network, 21 November 2022, available at: https://opennuclear.org/publication/brief-dprk-icbm-launch-18-november-2022-updates-21-november-2022-0
 Considering the necessary clearing between the tip of the launch canister and the tip of the missile, and the length of the gas generator, which is placed at the bottom of the launch canister.
 The RS-12M ICBM has a diameter of 1.8 m and a length of 20.5-21.5 m. See: Russia's Arms Catalog, Volume IV, Strategic Missile Forces, 1996-1997, Moscow: Military Parade; A.V. Karpenko, Российское ракетное оружие 1943-1993 г.: Справочник [Russian Missile Weapons 1943-1993: A Handbook], St. Petersburg: PIKA, 1993
 Dmitry Stefanovich, A Joint Nuclear Force?, Russian International Affairs Council, 30 March 2017, available at: https://russiancouncil.ru/en/analytics-and-comments/columns/riacdigest/a-joint-nuclear-force/
 Military Parade Marks 75th KPA Birthday, KCNA, 9 February 2023, available at: http://kcna.kp/en/article/q/abad1068ad4bd5dbd396e909231d648b.kcmsf
 Tianran Xu, Emerging Capabilities? The Unflown SLBMs of the DPRK, Open Nuclear Network, 25 July 2022, available at: https://opennuclear.org/publication/emerging-capabilities-unflown-slbms-dprk. Tianran Xu, DPRK Unveils Its Solid-Propellant ICBM Motor, Open Nuclear Network, 16 December 2022, available at: https://opennuclear.org/publication/dprk-unveils-its-solid-propellant-icbm-motor
 The UN Panel of Experts estimated that the Pukguksong-4ㅅ and Pukguksong-5ㅅhave a diameter of 2 m. See: S/2021/777, United Nations, 8 September 2021, available at: https://undocs.org/Home/Mobile?FinalSymbol=S%2F2021%2F777&Language=E&DeviceType=Desktop&LangRequested=False
 Tianran Xu, DPRK Unveils Its Solid-Propellant ICBM Motor, Open Nuclear Network, 16 December 2022, available at: https://opennuclear.org/publication/dprk-unveils-its-solid-propellant-icbm-motor
 Great Programme for Struggle Leading Korean-style Socialist Construction to Fresh Victory, On Report Made by Supreme Leader Kim Jong Unat Eighth Congress of WPK, KCNA, 9 January 2021, available at: http://kcna.kp/en/article/q/4bd89fa5293bdf0a82d3f4323d1636e2.kcmsf
 S/2013/337, United Nations, 11 June 2013, available at: https://www.undocs.org/Home/Mobile FinalSymbol=S%2F2013%2F337&Language=E&DeviceType=Desktop&LangRequested=False
 North Korea 2012 Parade - Full Version, video available at: https://www.youtube.com/watch?v=9sUaffsnJlc&ab_channel=compazine. North Korea Military Parade April 15, 2017, video available at: https://www.youtube.com/watch?v=rPz4pCEblYA&ab_channel=WeirdNKvideosarchive. Hwasong-14 launch video, July 28, 2017, video available at: https://www.youtube.com/watch?v=WgNViGZZ3pk&t=14s&ab_channel=MartynWilliams. Hwasong 15 ICBM launch video from KCNA, video available at: https://www.youtube.com/watch?v=dCHixMH_Gdo&ab_channel=FactChecker. North Korean Military Parade 2020 for the 75th Anniversary of the Workers Party of Korea, video available at: https://www.youtube.com/watch?v=v4cGa7arCuQ&t=7094s&ab_channel=PaektusanRevolutionaryArmy
 North Korean Military Parade 2020 for the 75th Anniversary of the Workers Party of Korea, video available at: https://www.youtube.com/watch?v=v4cGa7arCuQ&t=7094s&ab_channel=PaektusanRevolutionaryArmy
 北朝鮮 「朝鮮人民軍創建75周年慶祝閲兵式 (조선인민군창건 75돐경축 열병식) [Military parade marking the 75th anniversary of the Korean People's Army], video available at: https://www.youtube.com/watch?v=S8g-sZ-PBgA&t=7s&ab_channel=dprknow
 N. Korea's nighttime military parade: New ICBM, Kim Jong-un's daughter, video available at: https://www.youtube.com/watch?v=VbhJalwmGq4&ab_channel=KOREANOW