The Liaoning, China's first aircraft carrier, sails in the sea near Qingdao in eastern China's Shandong province in 2012. (Chinatopix via AP)

China will have so many aircraft carriers by 2030 that the South China Sea will be “virtually a Chinese lake,” a new U.S. study warns, arguing that the balance of power in the Asia-Pacific region was shifting away from the United States.

Meanwhile, President Obama’s strategic “rebalance” to Asia has neither been clearly enough explained nor sufficiently resourced to cope with rising threats from China and North Korea, the report by the Center for Strategic and International Studies found.

It said the United States should sustain and expand its military presence in the Asia Pacific, as well as accelerate efforts to strengthen the capabilities of its allies and partners.

The CSIS study was carried out after Congress required the Pentagon to commission an independent assessment of U.S. strategy in the Asia-Pacific region.

It concluded that Obama’s rebalance needed more attention and resources, especially as China has accelerated the pace of “coercive activities” and island-building in the South China Sea and the East China Sea, and North Korea has continued to develop its nuclear and ballistic missile capabilities.

“Chinese and North Korean actions are routinely challenging the credibility of U.S. security commitments, and at the current rate of U.S. capability, the balance of military power in the region is shifting against the United States,” it said.

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It argued that China would have multiple aircraft carriers in the region by 2030, allowing it to overawe other nations without necessarily having to behave in an overtly menacing fashion.

China formally announced at the end of last year that it was building a second aircraft carrier, and it is expected to build more in the years ahead.

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“For rival claimants in the South China Sea, this is a game changer,” the report said. “There will almost always be a Chinese CSG (carrier strike group) floating in contested waters, or within a half-day’s steaming time.”

Whether China has seized territory or negotiated a resource-sharing scheme with other claimants, “the South China Sea will be virtually a Chinese lake, as the Caribbean or the Gulf of Mexico is for the United States today,” CSIS said.

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That will also make U.S. naval operations in the South China Sea a risky proposition, other than through U.S. submarines.

The rebalance was supposed to be one of Obama’s top foreign policy priorities, but other international crises, including conflict in the Middle East and the rise of the Islamic State militant group, as well as tension with Russia, have sucked up much of the administration’s attention.

This report may fuel criticism that Obama has neglected the threats posed by China’s rise and North Korea’s belligerence.

CSIS identified three main U.S. goals in the region — protecting U.S. citizens and allies, promoting trade and economic opportunity, and promoting universal democratic norms — but expressed concern that the rebalance “may be insufficient to secure those interests.”

It argued that capping military resources at budget levels set by the Budget Control Act would “severely constrain implementation of the rebalance” and called for Congress “to forge a long-term bipartisan agreement to fund defense at the higher levels for which there is a broad consensus.”

It also complained that there was confusion throughout Washington and across the Asia-Pacific region about the rebalance, as well as concern about its implementation, partly because there has been no central statement explaining the strategy.

“Addressing this confusion will require that the executive branch develop and then articulate a clear and coherent strategy, and discuss that strategy with Congress as well as with U.S. allies and partners across the world,” the report recommended.

But the United States should also build up the ability of its allies and partners in the region to respond to rising threats.

“Securities challenges are increasingly outpacing the capabilities of frontline regional states,” it said.

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