After Chinese President Hu Jintao and Barack Obama show the world smiles and handshakes next week, the wait will begin for the next of the feuds that have regularly sapped trust between the two powers.
Their summit at the White House on Jan. 19 is sure to be garlanded in vows of friendship and respect that, however sincere, belie tensions that could upset ties between the world's top two economies, as they did in 2010.
In the summit build-up, both sides have promoted hopes for more stable ties, playing down disputes that flared last year over trade, currency and North Korea, and tensions over U.S. military presence in Asia, Taiwan, Tibet and human rights.
There needs to be a strong signal to both countries and to the world that the U.S. and Chinese leadership have a very firm commitment to working together not only in areas where they can cooperate but also in addressing some of the problems that have emerged recently, said Michael Swaine of the Carnegie Endowment for International Peace in Washington.
A jittery Asia and the wider world are watching to see if Hu and Obama can pull that off.
But a successful summit may only delay and perhaps dilute the next feud to test trust between the two nations, which are heavily interdependent economically but deeply disparate politically, said analysts.
China's abrupt flight testing of its first stealth fighter during this week's visit by U.S. Defense Secretary Robert Gates showed relations can face jack-in-the-box surprises even when a state visit beckons.
It's quite possible that after this visit, China-U.S. relations will remain relatively stable for a while, for say this year, said Jin Canrong, a professor at Renmin University in Beijing who studies China-U.S. relations.
But this can't be sustained for too long, because a visit can create a healthy atmosphere but can't alter the structure of China-U.S. relations and the conflicts that it generates.
Beyond trade disputes and wrangling over Taiwan or human rights, a bigger risk is an incident that spirals into crisis.
We've been incredibly lucky over the last 10 years that we've not had a very significant accident or collision of one sort or another with the Chinese military that has resulted in significant loss of life and a real escalatory problem, said James Mulvenon, a military analyst at Defense Group, Inc.
SLOUCHING EAGLE, SWAGGERING DRAGON?
A senior Obama administration official, who spoke on condition of anonymity, said the United States and China are in a unique and challenging relationship that has to be worked at even without troubles over North Korea and trade.
There are lots of structural reasons why there are challenges in the relationship, beginning with the challenge of an established power and a rising power, going to the fact that we do have differences in our political systems, our history, our culture, said the official.
The 2008 financial crisis has magnified those rifts.
Economic woes have weighed down a United States already sapped by two wars, while China's coffers and sense of entitlement at the table of world governance have swelled.
Obviously, there is a power transformation under way. It's not that China is catching up with the United States rapidly, but China is certainly moving up, said Jingdong Yuan, a China expert at the University of Sydney in Australia.
Increasingly, there is less willingness for China to simply take instructions from Washington on what to do.
The power shift has been magnified in the public eye. Surveys in both countries show many people believe -- wrongly -- that China's economy is already outgrowing America's.
Powerful constituencies in the United States worry that China's growing economic and military power could undermine U.S. prosperity and preeminence -- gutting American industry and seeking to drive the United States out of Asia.
Many in China, including officials and military officers, believe the United States is set on strangling their country's rise by strategic encirclement through military alliances with Japan and South Korea and a new embrace of India.
Both sides possess a kind of confrontational DNA, said Sun Zhe, a U.S.-China expert at Beijing's Tsinghua University.
A misreading of U.S. motives contributed to missed opportunities after Obama took office in 2009 and tried to embrace China as a partner in tackling the financial crisis and other global issues, U.S. analysts said.
The Chinese took that as weakness, said Stefan Halper, an American scholar at the University of Cambridge in England.
In past months, Chinese officials have made a point of reiterating that their position that China has neither the capacity nor the desire to challenge the United States as a superpower on the world stage.
'DOMINATE THE WORLD'
The notion that China wants to replace the United States and dominate the world is a myth, State Councillor Dai Bingguo, who advises Chinese leaders on foreign policy, wrote in an essay published late last year.
Yet striking a balance between realist modesty and aspirations for a bigger voice has proven difficult for China.
Hu also has to deal with domestic opinion ... and that opinion has strongly anti-American currents, said Shi Yinhong, an international relations expert at Renmin University in Beijing.
Optimists hope Hu's visit will buy time for the two powers to achieve a steadier footing and show they can work together on the global stage addressing economic imbalances, nuclear disputes and global warming.
Less optimistic analysts say trouble is inevitable.
There are many disputes between China and the U.S. that have been temporarily set aside, and any of them could well up under certain circumstances, leading to a fresh round of feuding between the two, Yan Xuetong, a prominent, hawkish Chinese security analyst, wrote in a recent essay.