WASHINGTON (Reuters) - Nobody but Kim Jong-un knows what he hopes to achieve with his saber-rattling campaign, but the young North Korean leader probably didn't set out to aid the United States, the sworn enemy of three generations of Kims, at the expense of his country's main ally, China.
In a boon for U.S. policy that can only add to China's frustration with Kim, North Korean bellicosity has helped reinforce an American strategy of rebalancing its security policies toward the Asia-Pacific region.
To a China that often sounds more wary of Washington than of Pyongyang, months of North Korean missile and nuclear tests followed by a daily stream of bloodthirsty war threats may be worrisome, but the U.S. reaction is even more troubling.
"We understand what kind of regime North Korea is, but we also understand that North Korea is playing games," said Sun Zhe, director of the Center for U.S-China Relations at Beijing's Tsinghua University.
"Most importantly, we are complaining that the United States is using military drills as an excuse to continue to do this (rebalancing), putting up B-2s and other advanced weapons systems," he said.
B-2 and B-52 bombers, radar-evading F-22s and anti-missile system vessels like the USS John S. McCain represented the initial U.S. response to North Korea's repeated, explicit threats to launch nuclear strikes against the United States.
The U.S. also said it would shift THAAD (Terminal High Altitude Area Defense System) to defend Guam from missile attack. And Tokyo's Yomiuri Shimbun newspaper said Japan would permanently deploy Patriot Advanced Capability-3 (PAC-3) anti-missile systems in Okinawa to counter North Korean missiles.
The U.S. deployments, although focused on North Korea and mostly temporary, could be adapted or expanded to counter the extensive array of anti-access military capabilities Beijing has built up to delay or prevent the arrival of American forces to areas near China in the event of conflict.
Chinese President Xi Jinping may have underscored Chinese ambivalence when he did not specifically name North Korea when he said no country "should be allowed to throw a region and even the whole world into chaos for selfish gain."
Xi's remarks at the Davos-like Bo'ao Forum on the Chinese island of Hainan might have been targeting Washington as well as Pyongyang, reflecting Chinese unease at the U.S. "rebalancing" or "pivot" policy of winding down wars in Southwest Asia and paying renewed attention to the Asia-Pacific region.
"In China, it's widely believed that the pivot is a containment strategy of China. Almost everyone sees it as that," Stephanie Kleine-Ahlbrandt, a Beijing-based China analyst for the International Crisis Group.
In a talk in Washington explaining the rebalancing policy and the Pentagon's response to North Korea, U.S. Deputy Defense Secretary Ashton Carter did not mince words in addressing Chinese complaints.
"North Korea's behavior is causing not just the United States, but others in the region to take action," he told the Center for Strategic and International Studies.
"If the Chinese find them the kinds of things they don't like to see, there's an easy way to address that, which is to talk to the North Koreans about stopping these provocations," said Carter.
Carter was forceful and unapologetic in presenting the rebalancing as a continuation of post-war U.S. policy that allowed allies Japan and South Korea, followed by Southeast Asia, China and India "to develop politically and economically in a climate that has been free from conflicts."
"It's good for us and it's good for everyone in the region. And it includes everyone in the region. It's not aimed at anyone, no individual country or group of countries," he said.
Carter said the coming drawdown of forces from Afghanistan would allow the U.S. Navy to shift to the Pacific region surface combatant ships, carriers and other intelligence, surveillance and reconnaissance vessels.
Analysts who accept the rebalancing as based on sound geo-strategic principles nevertheless say Pentagon statements and force deployments should not be the most visible face of the Obama administration's core Asia policy.
"We've oversold the military and undersold the diplomatic and economic components of the integrated strategy of the rebalance," said Douglas Paal, a former U.S. official who heads Asian Studies at the Carnegie Endowment for International Peace.
"The reaction we're getting from China is 'they're coming to get us, we've got to respond, we've got to step up our military development,'" he said.
When Secretary of State John Kerry visits China, Japan and South Korea later this week in his first trip to the region as the top U.S. diplomat, he will need to adjust his rebalancing sales pitch to China while he engages in Korea crisis diplomacy.
That will be a tall order in Beijing, where new President Xi is consolidating his rule with a political and military elite that is highly suspicious of U.S. motives.
"When the economic, political and cultural elements were tacked on to the pivot, the Chinese said 'oh, so now we're being encircled economically, politically and culturally, too," said Kleine-Ahlbrandt.
"The problem with trying to disabuse someone of a conspiracy theory is that any argument you make becomes part of the conspiracy, so I don't know if it's possible to convince the Chinese that it's not about encircling them," she said.
Additional reporting by Ben Blanchard in Beijing; Editing by Warren Strobel, Mary Milliken and Todd Eastham