Anne Penketh: Clinton won a promise – but does China mean to keep it?

As the Tiananmen Square protesters know only too well, political dissidence in China usually has one outcome – a one-way ticket to America, and exile.

If Chinese authorities really have agreed to allow Chen Guangcheng to remain in his homeland to study, and guaranteed the safety of his family, in a departure from traditional policy – and reports last night suggest that the deal may already be unravelling – the Obama administration will be able to claim a much-needed diplomatic coup only months before the presidential election in November.

But the question now is whether the Chinese will keep their word. As US Secretary of State Hillary Clinton said yesterday: "Making these commitments a reality is the next crucial task."

Remaining in China was the original choice of the "barefoot lawyer" but the precedents were not good. Indeed there were ominous reports last night that he left the American embassy for hospital because his family had received death threats.

The Chinese astrophysicist Fang Lizhi spent 13 months holed up in the US embassy after seeking shelter there following the Tiananmen massacre in 1989. He died in exile last month in Tucson, Arizona. In February, the former police chief of Chongqing city, Wang Lijun, was sent out of the US consulate into the waiting arms of Chinese police after he fell out with the now disgraced local party leader Bo Xilai. Mr Wang may face treason charges and has not been heard of since.

Neither side needed a crisis in relations, with Washington anxious to secure Chinese support on North Korea and Iran, two strategic challenges that could derail Mr Obama's re-election chances if they are not contained. But the economic stakes also couldn't be higher, with US Treasury Secretary Timothy Geithner and a large delegation accompanying Ms Clinton to Beijing.

If the US quiet diplomacy pays off – and that remains a big "if" – the denouement of the Chen drama will be another feather in the cap of Ms Clinton who led the administration's opening to Burma with a high profile meeting with opposition leader Aung San Suu Kyi last December. But her personal credibility is now on the line.

She has showed loyalty to Mr Obama, her former rival for the Democratic party presidential nomination. Despite denials, she is touted as a viable presidential candidate in 2016, whether or not Obama is re-elected.