U.S. military planners say the “Davidson Window” for a possible Chinese move on Taiwan is rapidly shrinking as 2026 approaches, and China ramps up its most aggressive drills yet around the island.

There is broad consensus in the Washington defense policy community, the Pentagon, and elected officials that China is the United States’ biggest foreign threat.

The report, produced each year by the Pentagon, warns Beijing is gearing up for conflict — potentially over Taiwan — within ...