The Pentagon chief also stressed trilateral cooperation with Tokyo and Seoul is crucial for regional stability even as South Korea is in political turmoil.
Key lawmakers grew frustrated with the F-35 program earlier this year, as critical upgrades stalled and jets piled up at Lockheed Martin's Texas factory.
In a first from Guam, the Missile Defense Agency intercepted a medium-range ballistic missile target off the coast using a Standard Missile-3 Block IIA.
Adopting Modular Open System Architecture will help the U.S. military field new technology faster and mass-produce legacy weapons, Navy officials argue.