A great power is a nation generally considered to have large amounts of military might and influence. While there is no established definition, for the purpose of this article, a great power is one of the top 10 nations by military spending according to the most recent report released by the Stockholm International Peace Research Institute (see latest report here). As of 2020, the great powers are therefore the United States, China, India, Russia, Saudi Arabia, France, Germany, the United Kingdom, Japan and South Korea.
While great power wars have declined greatly over time, some have argued that we should assign considerable probability to the prospect in the coming decades. In his post Big War Remains Possible Robin Hanson writes
The world is vast, eighty years is a long time, and the number of possible global social & diplomatic scenarios over such period is vast. So it seems crazy to base predictions on future war rates on inside view calculations from particular current stances, deals, or inclinations. The raw historical record, and its large long-term fluctuations, should weigh heavily on our minds.
When will be the next "Great Power" war?
This question will resolve as the earliest date after January 1, 2020 when at least 2 great powers are at war with each other.
Nations will be considered to be "at war" if any of the following are true:
One nation has formally declared war on another.
One nation is considered by the international community to be occupying territory claimed by the other AND there have been at least 250 casualties resulting from when the leaders of one nation ordered a strike on the other nation's military personnel.
Credible media sources consistently describe the relationship between the two nations as "at war."
For the purpose of this question, a great power is defined as one of the top 10 nations by their absolute (not relative) amount of military spending according to the most recent report released by the Stockholm International Peace Research Institute.
If this does not occur by December 29, 2199, this question will resolve as >December 29, 2199.