The world expected Barack Obama to win from Hu Jintao concessions the Chinese President wasn't in a position to deliver, writes John Garnaut.

Hours after Barack Obama landed in Beijing and headed to the St Regis Hotel, a cavalcade of black sedans travelled out the other way.

The Monday morning airport procession, against the traffic, was led by China's security chief, Zhou Yongkang. Without the customary fanfare, he slipped out of China to meet an old Sudanese friend accused of genocide in Darfur. Zhou's three-day visit to President Omar al-Bashir coincided with the US President's time in Beijing with President Hu Jintao and Premier Wen Jiabao. It was a vivid statement of how differently the US and China might view the world when they are running it together.

Obama brought some of his heaviest hitters to enlist China in confronting "the major challenges of the 21st century, from climate change to nuclear proliferation to economic recovery … challenges that neither of our nations can solve by acting alone."

Over three days, Obama and Hu spoke positively of each other's efforts but struggled to list concrete achievements on any Obama priority, despite nearly a year of focused preparation. Obama and his team spoke bravely if not convincingly about China being receptive to its message on Iran, North Korea and Pakistan and Afghanistan. Sudan never made it to the list. On China's human rights both sides plainly disagreed.

"I underlined to President Obama that given our differences in national conditions, it is only normal that our two sides may disagree on some issues," said Hu.

There was nothing about Hu's demeanour which suggested that he enjoyed his meetings with Obama. But for the Chinese state, even if the leaders failed to forge rapport or achieve policy breakthrough, it was a priceless three-day opportunity to manoeuvre a US President on their stage and endlessly project the image that America was down and China was up.

By some accounts, China's single highest diplomatic priority was not reducing the threat of rogue nuclear weapons on its doorstep or preventing the next economic meltdown, but getting Obama to say, on Chinese soil, that "Tibet is part of China", even though lesser American officials have conceded this many times before.

In Chinese diplomacy, form and content can be hard to disentangle.

China is a "ritual state", explains Australian National University China historian Geremie Barmé, which is "tirelessly reassuring itself and who is ever watching of its own stature and stateliness".

Elaborately choreographed spectacles like last year's Olympic Games, the October 1 Military Parade and this week's Obama visit are part of the fabric of Chinese politics.

"Whereas people may be galled by the nature of party rule or government misrule in their immediate lives, these highly codified rituals broadcast via the electronic and print media reinforce the sense that China is a rich and powerful nation, one that has realised its national mission," says Barmé.

Of course, not all Chinese were impressed by their "ritual-state" going to extraordinary lengths to prevent Obama from engaging freely with the Chinese public. To many, particularly among the internet-savvy youth, the contrast between the Chinese state's manifest insecurity and Obama's natural confidence could not have been more instructive.

"They put a condom on the President of the United States," wrote Wang Yukun at Sina, a popular website.

Obama handled Beijing's strictures with grace but it wasn't easy going. Bashir, in Khartoum, found security chief Zhou Yongkang a more obliging dance partner.

Zhou had taken with him a contingent that was almost as impressive as Obama's.

His Sudan entourage included Jiang Jiemin, the boss of Petrochina; Zhang Guobao, the head of energy policy at China's National Development & Reform Commission; Wang Jiarui, head of the Communist Party's International Department (a job that has more influence on Chinese foreign policy than the minister of foreign affairs) and Wu Shuangzhan, chief of the People's Armed Police.

Zhou could not have made his visit to Sudan without the party leadership considering how it might affect the Obama-Hu Jintao spectacle in Beijing. Ostensibly, however, he and Bashir were simply getting down to business. They unveiled the first Khartoum-Beijing direct flights, opened a Confucius Institute, signed an agriculture agreement and agreed to jointly pump yet more oil.

On Thursday night, long after Zhou had left Khartoum and Obama had left Beijing, China Central Television belatedly ran a two-minute news story on Zhou and Bashir lavishing praise upon each other.

The world is familiar with how Obama's agenda in China was constrained by his own domestic politics. He had squandered political credits with China by slapping tariffs on Chinese tyre and other exports in order to mollify American manufacturers. And China, it seemed, was preparing to cut a climate change deal with the United States that might have led to a legally binding agreement at Copenhagen - something that China sees as being in its national interest - but the US was not ready.

But Hu was also weighed down by domestic political challenges. One of the biggest may have been on display in Sudan this week.

Back in 1995 Zhou Yongkang was working his way to the top of China's biggest oil company, Petrochina. He had close connections with another oil industry veteran, Zeng Qinghong, who happened to be a powerbroker for the then president, Jiang Zemin. Zhou and Zeng were the drivers and Jiang was the decision maker behind China's hugely controversial decision to exploit Sudan's oil reserves at a time when Western companies could not afford the political or reputation risk, according to several Chinese oil industry and foreign policy sources.

This week, Zhou gave a modest account of that personal history.

''Fourteen years ago, then Chinese president Jiang Zemin and you made the strategic decision to start China-Sudan oil co-operation, and our bilateral pragmatic co-operation has since entered a stage of fast development," Zhou recounted to Bashir, on the delayed CCTV report.

Bashir was quick to give Zhou some personal glory.

"You are the important promoter of the Sudan-China oil project, the Sudanese people have special affection towards you," said Bashir. "Sudan-China oil co-operation not only brought Sudan oil but also peace."

The theme of Chinese news reports was the continuity of Chinese policy despite leadership change.

Earlier, a Bashir adviser, Mustafa Othman Ismail, had told Xinhua that the Sudan-China relationship was a "model" for the world. He added that "there had been no tensions and differences between Sudan and China under different leaderships in both nations."

Zhou left Petrochina in 1998 and Jiang stepped down from the presidency in 2002. But Chinese institutions can be shaped as much by invisible ties of patronage as official lines of power.

Sources in the Chinese and Western oil industries as well as Chinese and Western foreign policy strategists say Zhou continued to hold the reins of China's oil industry for many years after his official title changed. Some foreign policy strategists go further, claiming an Oil Gang drove the Chinese Government's more recent forays into Iran's oil and gas fields and even obstructed efforts by President Hu and others to support international sanctions against Sudan and Iran.

These days, Zhou heads China's secret and public security agencies as well as China's justice system. He is Jiang's most important ally and therefore a factional rival of Jiang's successor, Hu Jintao.

Another important Jiang ally, Li Changchun, controls the realm of propaganda, media freedom and internet censorship.

A majority of generals on the Central Military Commission - which controls the People's Liberation Army - were appointed by Jiang and he is said to remain the patron of some. The Chinese military gets a large say in strategic policy decisions, especially in areas of oil investment and con- flict zones.

Unfortunately for Obama, and perhaps the world, most of the concessions that Obama would have liked from Hu happen to be on turf the Chinese president does not confidently control.

Hu has to juggle the interests of factional rivals, giant state-owned corporations and an increasingly entrenched bureaucracy. Even if he wanted to, he could not unilaterally commit himself to what Obama appeared to put most effort into - a threat of sanctions against Iran.

"I would not say that we got an answer today from the Chinese, nor did we expect one on the subject," conceded Obama's deputy national security adviser, Ben Rhodes, on whether China agreed in principle to sanctions if Iran continued to misbehave.

Obama's first visit to China played badly with his travelling press corps but the degree of difficulty in what he was attempting was widely understated.

"I did not expect, and I can speak authoritatively for the President on this, that we thought the waters would part and everything would change over the course of our almost 2˝ -day trip to China," said Obama's press secretary, Robert Gibbs.

Gibbs may have been in damage control but he also had a point. The US cannot lead like it used to. It has to give China a more proportionate say. But both nations have huge adjustments to make before anyone can think seriously about them adroitly leading the world together.

John Garnaut is the Herald's China correspondent.