WASHINGTON The Obama administration, detecting what it sees as a shift in decades of Chinese support for North Korea, is pressuring China's new president, Xi Jinping, to crack down on the regime in Pyongyang or face a heightened U.S. military presence in its region.
In a flurry of exchanges that included a recent phone call from President Barack Obama to Xi, U.S. officials said they had briefed the Chinese in detail about U.S. plans to upgrade missile defenses and other steps to deter the increasingly belligerent threats made by North Korea's young leader, Kim Jong Un.
China, which has been deeply suspicious of the U.S. desire to reassert itself in Asia, has not protested publicly or privately as the United States has deployed ships and warplanes to the Korean Peninsula. That silence, U.S. officials say, attests to both Beijing's mounting frustration with the North and the recognition that its reflexive support for Pyongyang could strain its ties with Washington.
"The timing of this is important," Tom Donilon, Obama's national security adviser, said in an interview. "It will be an important early exercise between the United States and China, early in the term of Xi Jinping and early in the second term of President Obama."
While administration officials cautioned that Xi has been in office for only a few weeks and that China has a history of frustrating the United States in its dealings with North Korea, Donilon said he believed that China's position was "evolving."
Judging whether China has genuinely changed course on North Korea is tricky: Beijing appeared to respond to U.S. pressure before, only to backtrack. China, the North's only strong ally, has long feared the United States would capitalize on the fall of the North Korean leadership by expanding U.S. military influence on the Korean Peninsula.
Nor has China given clues about its intentions in its public statements, voicing grave concern about the rising tensions while being careful not to elevate Kim's stature.
Behind that taciturn reaction, Chinese analysts said, are internal debates within the Communist Party and the military about how to deal with Kim, and how vigorously to enforce the U.N. economic sanctions that China signed on to last month.
The White House said it was encouraged by how swiftly China supported the sanctions, which followed a North Korean nuclear test and a missile launch. But how energetically China has enforced them is a matter of debate, with some diplomats and analysts saying it has dragged its feet.
In the coming weeks, the White House will send a stream of senior officials to China to press its case, starting with Secretary of State John Kerry, who will travel to Beijing on April 13.
In the short run, officials said, the administration wants the Chinese to be rigorous in customs inspections to interdict the flow of banned goods to North Korea. More broadly, it wants China to use its leverage over Kim to persuade him to cease his provocations and agree to negotiations predicated on giving up his nuclear program.
On Friday, North Korea stoked tensions further by advising Russia, Britain and other countries that they might want to evacuate their embassies in Pyongyang in case of hostilities, according to Russian and British officials. Analysts dismissed the warning as a ploy to frighten the United States and its allies, perhaps to finally force concessions.
In Beijing, officials said Kerry also wanted to reinvigorate the dialogue with China on climate change. And the United States is pushing the Chinese leadership to crack down on the proliferation of cyberattacks on U.S. government and commercial interests originating in China.
Making progress on those issues will be easier if Washington is in sync with Beijing over North Korea. A week after Kerry's visit, Gen. Martin E. Dempsey, the chairman of the Joint Chiefs of Staff, will spend four days in China to try to improve communication between the U.S. and Chinese militaries.
Based on their meetings with Xi so far, administration officials said they believe he views Beijing's relationship with Pyongyang more pragmatically than his predecessor, Hu Jintao, whose reluctance to act against Pyongyang deeply frustrated Obama.