The Arleigh Burke-class guided-missile destroyer USS John S. McCain (DDG 56) launches a Standard Missile 2 during a missile exercise. John S. McCain is assigned to Task Force 71/DESRON 15, the U.S. 7th Fleet’s principal surface force. (U.S. Navy photo by Mass Communication Specialist 1st Class Jeremy Graham).

With a Russian surveillance ship lurking nearby, a crucial US missile defense test off the coast of Kauai went awry, when a salvo of SM-6 ship-fired missiles failing to intercept a medium-range ballistic missile target.

The Missile Defense Agency, in cooperation with the US Navy, said it conducted what it called Flight Test Aegis Weapon System 31, the Honolulu Star Advertiser reported.

“The objective of the test was to demonstrate the capability of a ballistic missile defense (BMD)-configured Aegis ship to detect, track, engage and intercept a medium-range ballistic missile target with a salvo of two Standard Missile-6 Dual II (BMD-initialized) missiles,” the agency said in a news release.

“However, an intercept was not achieved.”

Program officials have initiated an “extensive review” to determine the cause of any problems which may have prevented a successful intercept, the agency added.

A Russian spy ship loitering in international waters off Kauai for several days had delayed the missile test, USNI News reported.

US Pacific Fleet at Pearl Harbor said in a statement at the time that it was “aware of the Russian vessel operating in international waters in the vicinity of Hawaii, and will continue to track it through the duration of its time here.

“Through maritime patrol aircraft, surface ships and joint capabilities, we can closely monitor all vessels in the Indo-Pacific area of operations.”

An official previously said the test was delayed because the United States did not want the Russian vessel to “collect on” the effort.

It was not immediately clear if the Russian ship had departed the Hawaiian islands.

Kauai is home to the Pacific Missile Range Facility Barking Sands where the Navy and Missile Defense Agency test-fire a variety of missiles.

Senior Chief Fire Controlman Michael Cullinan monitors a radar console for air and surface contacts in the Combat Information Center (CIC) aboard the forward-deployed Arleigh Burke-class guided-missile destroyer USS Donald Cook. Credit: US Navy photo.

USNI News, which was the first to report the presence of the ship, said it was the Russian Navy Vishnya-class auxiliary general intelligence, or AGI, ship Kareliya (SSV-535).

The Vladivostok-based ship is one of seven AGIs specializing in signals intelligence, USNI News said.

The website reported in 2017 that the Kareliya had been mothballed for more than 10 years until January 2014 when a “comprehensive repair and retrofit of the ship” was performed.

USNI News said the Russian ship was operating 13 nautical miles west of Kauai in international waters. Territorial waters begin at 12 nautical miles.

“Russia is testing hypersonic weapons and maybe seeking insights into our missile systems that might enhance their hypersonic weapons ability to penetrate our defenses,” said retired Navy Capt. Carl Schuster, a former director of operations at US Pacific Command’s Joint Intelligence Center and an adjunct professor at Hawaii Pacific University.

He added that the missile defense test “is an intelligence opportunity that is hard to ignore.”

According to Military & Aerospace Electronics, the Aegis Weapon System is a centralized, automated, command-and-control and weapons-control system for the US Navy Burke-class destroyer and Ticonderoga-class cruiser; Spanish Álvaro de Bazán-class and F110-class frigates; and Japanese Kongo-class, Atago-class, and Maya-class destroyers.

Raytheon’s Aegis AN/SPY-1 advanced automatic-detect and -track multi-function phased-array radar and signal processor handles search, track, and missile guidance simultaneously, with a reported track capacity of more than 100 targets simultaneously.

Signals intelligence operations are common practice among rival and allied navies. Chinese and Russian ships routinely monitor US exercises.

Likewise, US signals intelligence aircraft and ships routinely operate off the coasts of China and Russia conducting similar operations.

During the Cold War, Russian surveillance ships commonly operated off the East Coast near the Naval Station Norfolk, Va., Naval Station Mayport, Fla. and the nuclear submarine base at Naval Submarine Base Kings Bay, Ga.