Mr Bush made very clear at Tsinghua University that he was indeed prepared to take on China's military over Taiwan. He spoke bluntly and his intentions, broadcast live on Chinese television, could not be ignored.

Former president Bill Clinton's deliberate ambiguity about how America would respond had raised expectations in China, prompting it to fire missiles, issue dire threats and lead many people to believe it was in China's grasp to force the situation when ready to do so.

It was widely assumed in China that America would not risk the lives of its soldiers to defend Taiwan against the interests of mighty China.

Professor Jin on Friday night was at pains to stress it was not in China's interests to allow America to turn Taiwan into another Israel because the price of war and instability was not worth paying.

Instead, he argued, it was in China's interests, and everyone else's, to stick as closely to the US as possible. 'If not it would bring ruin,' he said.

China would become a powerful economy in the 21st century, he said, implying it was not yet ready to become a military power that could stare down the US.

Before Mr Clinton's visit to China in 1998, Chinese military strategists had seemed confident they were cutting the military and technological gap with the US.

The confidence, even arrogance, was still evident in China's handling of the spy plane incident in April but now appears to have evaporated.

The demonstration of American military might during the Afghan war, followed by Mr Bush's apparent readiness to go to war unilaterally against members of the 'axis of evil', have changed things.

With Mr Bush signing off on huge increases in the military's budget, China's expectations that the American presence in the Asia-Pacific region would fade away, and its position supplanted by a rejuvenated China, have had to be adjusted.

In retrospect, China would have done better to use the favourable opportunities created by the more accommodating president Clinton to engage in direct talks with Taiwan instead of merely threatening it militarily.

Mr Jiang is now faced with the prospect of conducting talks with Taipei from a weaker position.

The same is true of North Korea, now under immense pressure to resume negotiations but under far less favourable circumstances.

Mr Clinton bent over backwards to reach a deal with Pyongyang before he left office. In Beijing, Mr Bush assured his hosts he would not start a war with North Korea but these reassurances came with conditions. He demanded from both China and Pyongyang that they stop exporting missile technology to clients in the Middle East and elsewhere.

After Mr Bush left, Foreign Ministry spokesman Kong Quan quickly declared that China was indeed ready to accommodate the US on arms non-proliferation issues.

If it does, China will be choosing to side with Washington at the expense of ties with Iran, Iraq and other client states. This in turn means it has less bargaining power with Mr Bush in its continuing efforts to persuade the Americans to stop supplying new weapons to Taiwan that are designed to maintain military parity across the strait.

By and large, the consequences of all this will be good for Hong Kong and the rest of the region because it reduces tensions and uncertainties.

Taipei is unlikely to be tempted to take steps towards independence and risk antagonising Beijing or irritating Mr Bush. Instead, the two sides will have to get down to work on building up a working relationship on establishing direct trade and communications.

The key question is how far Beijing will be prepared to go in order to get closer to Washington.

It could release members of the democratic party imprisoned after Mr Clinton left China, and bring forward its own political reform programme at least by making some token or symbolic gestures.

Mr Bush's mostly-sombre visit had a completely different tone to Mr Clinton's ebullient trip nearly four years ago.

If Beijing restarts talks with Taiwan, then it is also possible it could reopen contacts with the Dalai Lama and his exiled government. These were broken off in the mid-1990s during the row over the Panchen Lama, one of the most important clerics in Tibetan Buddhism. A 12-year-old boy nominated by the Dalai Lama as the reincarnated Panchen Lama disappeared into Chinese custody in 1995.

After Mr Clinton's direct appeal, China was poised to invite the Dalai Lama to visit, but for unknown reasons dropped the initiative.

The most interesting question is what China could do to satisfy an American leader who has emphasised the importance of religious freedom even more than his predecessors.

At the same time, Mr Jiang has been so determined to smash Falun Gong he has also staked out a tougher position on organised religion than his predecessors.

There will be close monitoring of whatever steps China takes in dealing with non-registered protestant groups, the underground Catholic Church, Tibetan Buddhists and many other groups struggling to develop some autonomy from the state.

So far Mr Jiang's inclination seems either to suppress them or to find a way to allow them to register so the state can better supervise them, rather than to grant all groups a higher degree of freedom of association.

With both Vice-President Hu Jintao and Mr Jiang scheduled to visit the US this year, China must use these opportunities and grab the attention of the Bush team.

Otherwise, the Chinese leadership probably fears that Mr Bush will do whatever he wants to do in Iraq.

Having worked so hard to raise China's profile on the international stage in recent years, all this makes for uncomfortable choices for Mr Jiang.

He may have come away from the meetings with Mr Bush convinced China's influence on global decision-making, in particular America's plans for Iraq, could be declining rather than growing.

As soon as Mr Bush left, Mr Jiang immediately phoned Russian President Vladimir Putin and Pakistani President Pervez Musharraf. It was an unusual step and may show that he wants to find ways of co-ordinating their tactics to make sure Mr Bush heeds their concerns.

Jasper Becker is the Post's Beijing bureau chief