Their targets? Pacific Command is the US military’s headquarters for the Asia-Pacific region. The US Navy, Air Force, Army and Marine Corps each have their own Pacific headquarters on Oahu. The National Security Agency also keeps an intelligence center in central Oahu.
There is a major missile defense testing site on the island of Kauai. A high-powered missile defense radar capable of tracking a baseball-sized object 4,000km away — called the Sea-Based X-band Radar — visits Pearl Harbor regularly.
The reconnaissance goes both ways. The US is eager to gather intelligence on new ships, planes and other equipment China is adding to its military.