A war between Russia and Europe is short-term beneficial to the U.S. (increased exports, weakening Russia, NATO control), China (cheap resources, geopolitical vacuum), and to a lesser extent Iran, Turkey, and India (economic and mediating gains). The arms industry thrives due to rising demand. The war is detrimental to Europe (economic downturn, military risks), Russia (resource depletion, isolation), and the global economy (inflation, recession). Long-term, China gains the most, as the weakening of the West and Russia accelerates a multipolar world where Beijing dominates. The U.S. will prefer to freeze the conflict once risks (e.g., nuclear escalation or China’s rise) outweigh benefits.

It will be beneficial for the U.S. to stop the war when:

Economic damage to Europe threatens U.S. markets (2026–2027, if the EU recession deepens).
China becomes a clear threat in Asia (e.g., rising tensions over Taiwan).
The risk of nuclear escalation exceeds 10–15% or Russia nears collapse (GDP drop of 10%+).
Domestic pressure in the U.S. (inflation, protests) makes war support unpopular.

Most likely, this will occur in 2026–2028 if current trends persist. The U.S. will prefer a frozen conflict (e.g., through Ukraine negotiations) to lock in Russia’s weakening, preserve Europe as an ally, and focus on China while minimizing its own losses.