Esper's Asia visits illustrate the central feature of a revamped U.S. defense strategy: Focus first on China as a threat to U.S. global predominance, rather than remain bogged down in a generation-long fight against extremist groups.
Esper was flying to South Korea on Wednesday for consultations on jointly defending against North Korea, whose nuclear arsenal remains a key focus for Pentagon war planners.
With China's disputed territorial claims in the South China Sea in mind, Esper also will visit Vietnam, a former U.S. enemy, as well as the Philippines, a longtime ally.
The Vietnamese, who contest some of China's claims in the South China Sea, have increasingly looked to Washington as a security partner, despite political differences.
Esper says that implementing the new defense strategy, which he inherited from his predecessor, former Defense Secretary Jim Mattis, is a work in progress.