WASHINGTON -- Amid mounting tensions with North Korea, the Pentagon has delayed an intercontinental ballistic missile test that had been planned for next week at Vandenberg Air Force Base in California, a senior defense official told The Associated Press on Saturday.

The official said Defense Secretary Chuck Hagel decided to put off the long-planned Minuteman 3 test until sometime next month because of concerns the launch could be misinterpreted and exacerbate the Korean crisis. Hagel made the decision Friday, the official said.

The test was not connected to the ongoing U.S.-South Korean military exercises that have been going on in that region and have stoked North Korean anger and fueled an escalation in threatening actions and rhetoric.

North Korea's military warned earlier this week that it was authorized to attack the U.S. using "smaller, lighter and diversified" nuclear weapons. And South Korean officials say North Korea has moved at least one missile with "considerable range" to its east coast - possibly the untested Musudan missile, believed to have a range of 1,800 miles. U.S. officials have said the missile move suggests a North Korean launch could be imminent and thus fuels worries in the region.

Pyongyang's moves come on the heels of the North's nuclear test in February, and the launch in December of a long-range North Korean rocket that could potentially hit the continental U.S. Added to that is the uncertainty surrounding the intentions of North Korea's new young leader, Kim Jong Un.

Meanwhile, North Korea has been angered by increasing sanctions and ongoing U.S.-South Korean military exercises, which have included a broad show of force ranging from stealthy B-2 bombers and F-22 fighters to a wide array of ballistic missile defense-capable warships. The exercises are scheduled to continue through the end of the month.

This past week, the U.S. said two of the Navy's missile-defense ships were moved closer to the Korean peninsula, and a land-based system is being deployed to the Pacific territory of Guam later this month. The Pentagon last month announced longer-term plans to beef up its U.S.-based missile defenses.

While Washington is taking the North Korean threats seriously, U.S. leaders continue to say that they have seen no visible signs that the North is preparing for a large-scale attack.

The defense official, who was not authorized to speak publicly about the Minuteman 3 test delay and requested anonymity, said U.S. policy continues to support the building and testing of its nuclear deterrent capabilities. And the official said the launch was not put off because of any technical problems.

The globe-circling intercontinental ballistic missiles make up one of the three legs of America's nuclear arsenal. There are about 450 Minuteman 3 missiles based in underground silos in the north-central U.S. The other two legs of the nuclear arsenal are submarine-launched ballistic missiles and weapons launched from big bombers, such as the B-52 and the stealthy B-2.

The traditional rationale for the "nuclear triad" of weaponry is that it is essential to surviving any nuclear exchange.

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