Global Developments: Mid–Late December 2025
Assessment Period: 15–28 December 2025
Current Status: Condition Green – DEFCON 5
Assessment: No imminent nuclear threats at this time
Over the past two weeks, a series of developments across East Asia, Europe, and the Middle East have underscored the continuing erosion of long-term strategic stability in the global nuclear environment. None of these events, taken individually, represent an immediate nuclear crisis. However, collectively they illustrate accelerating trends in force modernisation, doctrinal compression, and rhetorical escalation among multiple state actors.
This briefing examines key developments with potential relevance to nuclear risk and deterrence stability.
South Korea Completes Fielding of KTSSM
The Republic of Korea’s Defence Acquisition Programme Administration (DAPA) has confirmed that fielding is now complete for the Korean Tactical Surface-to-Surface Missile (KTSSM). This milestone represents the full operational deployment of an indigenous precision strike system designed to neutralise hardened and time-sensitive targets.
KTSSM is intended primarily as a conventional deterrent against North Korean artillery, missile, and command infrastructure. Its guidance systems and strike accuracy provide South Korea with enhanced first-response and counter-strike options without reliance on nuclear escalation.
From a strategic perspective, the completion of KTSSM fielding strengthens Seoul’s conventional deterrence posture and may reduce incentives for early escalation in a crisis. At the same time, it contributes to an increasingly dense missile environment on the Korean Peninsula, where overlapping offensive and defensive systems shorten warning times and complicate escalation management.
North Korea Unveils Nuclear-Powered Submarine
North Korea has publicly unveiled what it claims is its first nuclear-powered submarine, marking a significant symbolic step in its long-term effort to develop a survivable second-strike capability. The vessel was presented in a highly choreographed event, emphasising its strategic significance rather than its technical maturity.
Independent verification of the submarine’s reactor capability and operational readiness remains limited. Historically, nuclear propulsion has posed severe technical challenges for North Korea. Nonetheless, the regime’s intent is clear: to project an image of expanding and diversifying nuclear delivery options.
This unveiling coincided with multiple weapons tests overseen personally by Kim Jong Un, including long-range cruise missiles and other strike systems. North Korean state media framed these activities as exercises in deterrence readiness ahead of a major party congress expected in early 2026.
Even if full operational capability remains uncertain, the strategic signalling value of a nuclear-powered submarine should not be underestimated. Maritime nuclear platforms complicate detection and tracking, and their mere existence alters regional threat perceptions, particularly for South Korea, Japan, and the United States.
Russia Moves Oreshnik Missiles into Belarus
Satellite imagery and Western analytical assessments indicate that Russia has begun deploying the Oreshnik intermediate-range missile system within Belarusian territory. These missiles are believed to be dual-capable, able to carry either conventional or nuclear warheads.
The forward placement of such systems significantly reduces flight times to European targets compared to launches from within Russia proper. This compression of decision time increases the risk of misinterpretation and reduces margins for diplomatic or military de-escalation in a crisis.
Belarusian authorities have acknowledged the deployment, while Russian officials frame it as a defensive response to NATO force posture and missile developments in Europe. Regardless of intent, the effect is a further destabilisation of the European security environment, particularly as arms-control frameworks governing intermediate-range missiles remain defunct.
Japan Reaffirms Its Non-Nuclear Commitment
Japan has formally reaffirmed its adherence to the Three Non-Nuclear Principles—not possessing, producing, or permitting the introduction of nuclear weapons—following remarks by a senior official that briefly raised speculation about potential nuclear armament.
This clarification reinforces Japan’s longstanding policy and its reliance on extended deterrence provided by the United States, combined with advanced conventional military capabilities.
In a region where both China and North Korea closely scrutinise Japanese defence debates, the reaffirmation serves to reduce near-term proliferation risk. It also underscores Tokyo’s effort to balance deterrence needs with constitutional, political, and historical constraints.
China Expands Operational ICBM Deployment and Alters Readiness Posture
A Pentagon assessment released during the reporting period concludes that China has likely loaded more than 100 intercontinental ballistic missiles into newly constructed silo fields near the Mongolian border. This represents a transition from infrastructure expansion to active operational deployment on a significant scale.
In parallel, multiple analyses indicate that China is moving toward elements of a launch-on-warning posture. Such a shift would allow missile launches based on early-warning data rather than confirmed nuclear detonations, substantially shortening decision timelines.
China maintains its declared no-first-use policy and frames its nuclear expansion as a defensive response to U.S. and allied capabilities. However, larger deployed arsenals combined with higher readiness levels inherently increase escalation risks, particularly during periods of heightened tension or degraded situational awareness.
These developments mark one of the most consequential shifts in the global nuclear balance in decades, moving China from a relatively small deterrent force toward a posture approaching peer-level strategic competition.
Iran Declares a “Full-Fledged War” with the West
Iranian President Masoud Pezeshkian has declared that Iran is engaged in a “full-fledged war” with the United States, Israel, and Europe. While this statement does not constitute a formal declaration of war under international law, it represents a significant escalation in rhetoric.
The declaration follows a year marked by direct military confrontations, including strikes on Iranian nuclear facilities and subsequent Iranian missile attacks against Israeli targets. Tehran characterises the conflict as multidimensional, encompassing military, economic, and political warfare.
Although most believe that Iran does not currently possess nuclear weapons, its ballistic missile capabilities, nuclear latency, and regional proxy network make its posture relevant to broader nuclear risk dynamics, particularly in scenarios involving escalation between nuclear-armed states.
Conclusion
The global nuclear landscape at the close of 2025 is characterised less by immediate crisis than by accelerating structural risk. Strategic competition is intensifying, arms-control mechanisms remain largely absent, and multiple actors are reducing the time available for human decision-making in nuclear scenarios.
The DEFCON Warning System continues to assess these developments under Condition Green – DEFCON 5, reflecting the absence of imminent nuclear threats while recognising persistent long-term instability.
Ongoing monitoring will focus on force readiness changes, doctrinal shifts, and escalation indicators across all nuclear-armed and nuclear-relevant states.
The DEFCON Warning System is a private intelligence organisation which has monitored and assessed nuclear threats by national entities since 1984. It is not affiliated with any government agency and does not represent the alert status of any military branch. The public should make their own evaluations and not rely on the DEFCON Warning System for any strategic planning.
At all times, citizens are urged to learn what steps to take in the event of a nuclear attack.
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