This question is from the 2023 ACX prediction contest. It resolves as per Scott Alexander's judgement, unless such judgement is obviously wrong as per a strong majority of Manifold traders.

Some clarification from the Google form:

A formal cease-fire will count, as long as it remains substantially in effect at the resolution time. Minor violations won’t count against this as long as both sides and the international media agree it is still substantially in effect. An informal cease-fire will count if it involves at least one month without significant military action and the international media dubs it a de facto cease fire. A cease-fire which is signed but then substantially broken before 1/1/24 will not count.