The US is "prepared" to engage in a 'conventional' war with North Korea but it requires time to adjust to the new front, says the military.

Gen. George Casey appearing at the Center for Strategic and International Studies on Thursday said the US was ready to enter an old-fashioned war with North Korea if necessary.

However, he said, "It would probably take us a little bit longer to shift gears" away from the type of counterinsurgency fighting that now occupies the Army. Casey was referring the US two wars in Iraq and Afghanistan.

"We'd move forces as rapidly as we could get them prepared," Casey insisted.

The US army's chief of staff refrained from suggesting how long it would take to redeploy the army in the new front on the Korean peninsula, but said that the US army was "combat seasoned" and could move quickly.

"The mechanical skills of artillery gunnery and tank gunnery come back very, very quickly," he said. "The harder part is the integration - that really brigade level and above of massing fires and effects in a very constricted period of time as opposed to what you do in a counterinsurgency over a much longer extended period of time."

North Korea violated international treaties by conducting a nuclear test and test-firing nuclear-capable missiles, despite international warnings and UN Security Council resolutions.

While thousand of US soldiers stationed in South Korean bases are on high alert, the US defense secretary, Robert Gates, maintains that North Korea's actions have not reached a crisis level that would warrant additional US troops in the region.

"What we do have, though, are two new developments that are very provocative, that are aggressive, accompanied by very aggressive rhetoric," Gates said. "And I think it brings home the reality of the challenge that North Korea poses to the region and to the international community."

RB/MMN