The U.S. Defense Department has delayed an intercontinental ballistic missile test that had been planned for next week at an Air Force base in California amid mounting tensions with North Korea, a senior defense official told The Associated Press.   

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 Saturday.

The test was not connected to the ongoing annual U.S.-South Korean military exercises in that region that have angered North Korea.

The North's military warned this week that it was authorized to attack the U.S. using ``smaller, lighter and diversified'' nuclear weapons. 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 (2,890 kilometers).

U.S. officials have said the move suggests a North Korean launch could be imminent. But while Washington is taking the North Korean threats seriously, U.S. leaders say they have seen no visible signs that the North is preparing for a large-scale attack.

North Korea held its latest nuclear test in February, and in December it launched a long-range rocket that potentially could hit the continental U.S. Increasing tensions is the uncertainty around the intentions of the country's new young leader, Kim Jong Un.

North Korea has been angered by increasing sanctions and the 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 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 strengthen its U.S.-based missile defenses.

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. 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. About 450 Minuteman 3 missiles are based in underground silos in the 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.(AP)