AFP America's top military officer said on Friday that a rocket North Korea plans to launch next month has a range that could possibly reach Hawaii.

Asked if the North Korean rocket could reach the US states of Hawaii or Alaska, Admiral Mike Mullen told CNN: "In some cases, yes, they could probably get down to Hawaii."

International concern has been mounting about North Korea's announcement it would launch a communications satellite between April 4 and 8.

The United States, Japan and other allies believe Pyongyang is using the launch to test a ballistic missile that could, in theory, cross the Pacific to reach North America.

The launch, combined with North Korea's atomic weapons, were cause for serious concern, the admiral said.

Mullen added the regime's missiles did not yet have a range that could strike the western coast of the US mainland.

Arms experts say North Korea has yet to demonstrate it has the ability to construct and fit a nuclear warhead onto a missile.

The launch, even if it is for a satellite as announced by North Korea, would help the regime in developing a long-range missile threat, said Mullen, the chairman of the US Joint Chiefs of Staff.

"What concerns me is the guidance, the engineering, the engines, those are all identical to the kinds of capabilities you'd put on a ballistic missile," he said.

Japan gave its military the green light on Friday to shoot down any incoming North Korean rocket. And Japanese and US warships have already deployed ahead of the April 4-8 window.

North Korea has said shooting down its rocket would be treated as act of war.

The last time North Korea launched a long-range Taepo-dong 2, on July 4, 2006, the missile failed seconds after launch.

Mullen declined to comment on any possible US military response to a rocket launch.

Other US commanders have said they have confidence the US military had the ability to shoot down any missile threatening the United States using sea-based or land-based missile defense weaponry.

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