As of December 31, 2027, what will be the status of the Russia-Ukraine war?

rationale:

Baseline and Modal Outcome (Ongoing War). The single most likely outcome remains continued active or frozen war without a holding formal agreement (61%). The battlefield is largely static and attritional, with Russia holding roughly 19–20% of Ukraine and achieving incremental net gains of only ~1.2 km²/day in mid-2026 2 sources. At the diplomatic level, the two sides retain fundamentally incompatible core demands: Russia demands the remainder of Donbas, Kherson, and Zaporizhzhia alongside international recognition, while Ukraine refuses to cede its territory en.wikipedia.org. The Kremlin explicitly rejects a simple front-line freeze, treating the capture of Donbas as essential reuters.com. Furthermore, the resolution criteria strictly require an agreement to be in effect and holding on December 31, 2027; partial arrangements like an "air ceasefire" or a signed deal that subsequently collapses into renewed fighting would still resolve as no agreement 2 sources.

Ceasefire at Current Lines. Despite the diplomatic impasse, mounting structural strains could eventually force a settlement, giving a ceasefire or peace agreement at roughly current lines a 22% chance. Ukraine publicly proposes that diplomacy should begin from the current front line president.gov.ua, and Russian economic stress or domestic constraints could theoretically shift Moscow's maximalist stance over the next 17 months reuters.com. However, historical timelines for a diplomatic breakthrough have repeatedly proven too optimistic metaculus.com, and this estimate reflects appropriate skepticism that a lasting bilateral armistice can be achieved and maintained on current lines without significant concessions.

Ceasefire with Significant Russian Gains. If a deal is forced, there is a material chance (10%) that it requires Ukraine to cede additional territory, or that it follows further slow Russian captures in the Donetsk "Fortress Belt" (e.g., Pokrovsk, Kostiantynivka) prior to a freeze 2 sources. Plausible US-brokered proposals, such as a demilitarized zone, might require a Ukrainian withdrawal from the remainder of Donetsk Oblast to meet Moscow's red lines en.wikipedia.org. This would trigger the resolution condition for Russia controlling significantly more territory than in August 2026, making this a distinct and realistic pathway to a holding agreement.

Low-Probability Tail Risks. The remaining outcomes are highly unlikely. Ukrainian recapture of significant territory (2%) is near-negligible given the current force balance, manpower shortages, and the failure of recent large-scale offensives 2 sources. Conversely, a complete Ukrainian state collapse or capitulation (2%) is forestalled by secured Western financing, including a €90 billion EU support loan for 2026–2027 and equivalent NATO military aid pledges 2 sources. Russia has demonstrated an inability to achieve operational breakthroughs even with a manpower edge understandingwar.org. "Other" outcomes (3%) cover remote scenarios such as a direct NATO-Russia confrontation following spillover incidents, or a sudden Russian regime rupture understandingwar.org.