A long thought experiment about how a third world war could unfold, mostly bad news for the Baltics, Taiwan, South Korea, and any country near Russia or China.

• A US-Russia war over Ukraine would likely stay conventional, with the US rolling back Russian gains in about 10 weeks thanks to better training, night fighting, and air power.
• Russia is now seen as militarily weak after Ukraine, but it could rebuild and threaten the Baltics or Finland with sheer mass of older tanks within a decade.
• China is the bigger long-term threat and is preparing for war over Taiwan, which makes most of the world's semiconductors.
• A Taiwan war would devastate the island's dense cities, and China could also strike Japan, the Philippines, and South Korea to push the US out of the region.
• North Korea could open a second front by smuggling nuclear, chemical, or biological weapons into South Korean ports, starving the country of food and fuel.
• Western weapon stockpiles are dangerously low after arming Ukraine, and resupply could take a decade.

Outlook: Taiwan is the most likely flash point for the next big war, with China prepared to fight now and the US racing to arm allies in the Pacific.