The next U.S. secretary of defense should make sure to prepare for the possibility of "limited military campaigns" against North Korea, an American think tank said, pointing out the U.S. and South Korea lack contingency plans for "limited-war scenarios."

The Center for a New American Security made the recommendation in a set of policy suggestions to Ashton Carter, President Barack Obama's nominee to be the next secretary of defense, saying the allies should be prepared in case a diplomatic solution to the North's nuclear program fails.

"The secretary of defense is uniquely responsible for military contingency plans, and Carter will therefore need to ensure that DOD (the Department of Defense) is preparing for the possibility of limited military campaigns on the Korean Peninsula," CNAS said.

"The United States and ally South Korea have long prepared for total war with North Korea, and in recent years the prospect of a North Korean collapse as well. Limited-war scenarios, however, fall in between these two extremes and demand a distinct set of objectives, resources and planning assumptions, beyond simply planning to parry a single provocation," it said.

A diplomatic solution to the North Korean nuclear program might still be possible, but if that ultimately fails, the U.S. and South Korea must be prepared for the "political-military realities that follow," the think tank said.

The Senate Armed Services Committee held a confirmation hearing for Carter last week, and the widespread view is that the former deputy secretary of defense will be confirmed as the Republicans, controlling the Senate, do not oppose his nomination.

Carter, a hawk on North Korea, will likely support CNAS' suggestion.

In 2006, Carter openly called for a pre-emptive strike on a North Korean long-range missile that was being readied for a test-launch, claiming that the risk of inaction in the face of North Korea's race to threaten the U.S. would be greater than the risk associated with a pre-emptive strike.

CNAS also emphasized the seriousness of the North's nuclear program.

"No actor is more capable of creating a regional conflict than North Korea. Pyongyang's recent attack on Sony has attracted attention for its novelty, but the country's nuclear and missile threat is a more lethal danger that continues to grow unconstrained," it said.

Though the size and shape of Pyongyang's arsenal is unclear, research, development and testing of delivery vehicles suggest it is moving in the direction of "eventually establishing a survivable nuclear capability."

This "poses a strategic problem insofar as a secure deterrent convinces North Korea it can launch provocations or even limited military campaigns without risk of nuclear war," the think tank said, adding that nothing in U.S. policy today suggests the North's nuclear progress will be halted or rolled back.

The policy report also advised Carter to continue to make Obama's "rebalance to Asia" an "indisputable fact." Even in the face of global challenges, it is essential to strengthen U.S. influence to preserve peace and adapt a prosperous, rule-based regional order, it said.

The report said the U.S. should continue to work closely with Japan for regional security and play a leading role in allaying any concerns Japan's neighbors might have by explaining the benefits of Japanese security contributions and making those contributions a key part of the alliance.

To help remove potential friction points with China, the report suggested that the U.S. continue institutionalizing military-to-military engagement and inject transparency into contested maritime areas by constructing a requirements road map for a regional common operating picture among participants. (Yonhap)