The distinctive missile telemetry ship MV Pacific Collector is in port at Aloha Tower, possibly for a key upcoming ballistic missile defense test.
The 393-foot ship with twin domes housing 24-foot antennas is owned by the U.S. Department of Transportation's Maritime Administration and used in support of U.S. Missile Defense Agency missions.
Spokesman Chris Johnson said the agency doesn't usually talk about assets used in a missile defense test until after the fact, but did confirm the next flight intercept test of the ground-based mid-course ballistic missile defense system is planned for late May.
That test will be the first time a ground-based missile interceptor launched from California attempts to smash into a "threat-representative" intercontinental ballistic missile in its mid-course over the Pacific, the Missile Defense Agency said.
Thirty-six ground-based interceptors -- a number increasing to 44 this year -- are in place in Alaska and California to theoretically defend the United States, including Hawaii, against nuclear missile attack. However, a Pentagon weapons testing office rated the $40 billion system in December as having low reliability.
The test will be closely watched to see whether upgrades work at a time when North Korean ballistic missiles are being test-fired on an accelerated basis. Adm. Harry Harris, head of U.S. Pacific Command, recently told Congress that North Korean leader Kim Jong Un "is clearly in a position to threaten Hawaii today."
Vice Adm. J.D. Syring, director of the Missile Defense Agency, gave his assessment of North Korea in April 2016.
"In addition to the Taepo Dong 2 space launch vehicle/ICBM, North Korea is developing and has paraded the KN-08 road-mobile ICBM and an intermediate-range ballistic missile with a range greater than 3,000 km (1,864 miles)," Syring told the House Armed Services Committee.
Pacific Collector was stationed in the "broad ocean area" northeast of the Hawaiian Islands for an intercept test on June 22, 2014. The ship processes missile telemetry primarily in the mid-course and terminal phases of flight.
A ground-based missile fired from Vandenberg Air Force Base in California successfully knocked out an intermediate-range ballistic missile target launched from the U.S. Army's Reagan Test Site on Kwajalein Atoll.
The ground-based system has a record of nine successful intercepts out of 17 attempts since 1999 -- translating to a 53 percent success rate. The upcoming test, designated FTG-15, will evaluate the upgraded "Configuration 2" booster and "Capability Enhancement-II Block 1" exo-atmospheric kill vehicle, which smashes into a warhead to disable it.
During a Jan. 28, 2016, flight test -- but not a planned intercept -- a defensive missile fired from California zeroed in on a target missile launched from a C-17 cargo plane west of Hawaii. The test of alternate "divert thrusters" on the exo-atmospheric kill vehicle was deemed a success by the Missile Defense Agency.
However, the Pentagon's chief weapons testing office later said that a circuit board associated with one of the divert thrusters experienced a short and did not command the thruster to turn on for the later part of the test.