WASHINGTON — The aircraft carrier Carl Vinson and her strike group have been ordered to cancel planned visits to Australia and head back to Korean waters, the U.S. Navy announced Saturday night. The carrier was already operating in the western Pacific and had just visited Singapore.

"U.S. Pacific Command ordered the Carl Vinson Strike Group north as a prudent measure to maintain readiness and presence in the Western Pacific," Cmdr. Dave Benham, a spokesman for the command, said in a statement.

"Third Fleet ships operate forward with a purpose: to safeguard U.S. interests in the Western Pacific," Benham continued. "The number one threat in the region continues to be North Korea, due to its reckless, irresponsible, and destabilizing program of missile tests and pursuit of a nuclear weapons capability."

North Korea has an aggressive campaign to develop ballistic missiles with a stated aim of attacking the United States. The most recent launch, on April 5, featured what U.S. defense officials called an extended range Scud missile, a medium-range weapon. The missile apparently suffered an in-flight failure and crashed in the Sea of Japan after travelling about 40 miles.

In another test on March 6, North Korea simultaneously launched four ballistic missiles which flew about 620 miles before falling into the sea. Apparently as a result, the United States accelerated the planned deployment of a Terminal High-Altitude Area Defense system, or THAAD, to South Korea.

The Vinson strike group is under the operational control of the Navy’s San Diego-based Third Fleet, a departure from the standard command structure of having the Japan-based US Seventh Fleet control U.S. ships in the western Pacific. The move, dubbed the Third Fleet Forward Initiative, is intended to increase complexity by giving potential opponents more commanders to outguess. The Third Fleet is commanded by Vice Adm. Nora Tyson, reporting to the U.S. Pacific Fleet in Pearl Harbor. Pacific Fleet in turn reports to Adm. Harry Harris, commander of U.S. Pacific Command, who ordered the Vinson group north.

While Third Fleet has controlled surface action groups on Western Pacific deployments, this is the first time since World War II the command has controlled a carrier strike group west of the International Date Line, a spokesman said. The fleet in World War II was led by legendary Adm. William Halsey.

The Vinson left for deployment on Jan. 5 and, like the last few Pacific fleet carrier cruises, is expected to spend its time patrolling the western Pacific rather than move on to the Middle East under U.S. Central Command control. The Vinson and her strike group operated in the South China Sea in February, exercised with Japanese warships in early March, and most recently took part in Exercise Foal Eagle with South Korean forces, during which the carrier spent five days pier side in the Korean port of Busan.

The Vinson, cruiser Lake Champlain and destroyer Wayne E. Meyer were visiting Singapore’s Changi naval base and left April 8 as scheduled. The destroyer Michael Murphy was operating in Malaysian waters and will rejoin the strike group, a Navy spokesman said. Vinson is carrying the aircraft of Carrier Air Wing Two.

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