There are reasons why reports that the Taliban have advanced within 70 miles of Pakistan's capital may not be quite as alarming as they at first appear. One is that Islamabad is, relatively speaking, not so very far from the tribal areas where the Taliban has long been powerful. Another is that the Taliban is adept at playing cat-and-mouse games, advancing only to withdraw when it encounters determined opposition, and, by dispatching troops to the area, the Pakistan government has shown that it intends to draw a line.

But it must also be admitted that this is scant, and probably temporary, consolation. If, as it appears, Taliban forces have taken over the district of Buner, this is a significant advance and one that will not be easy to reverse. It threatens to alter the balance of advantage between the Taliban and the Islamabad government. Pakistan's future, both as a democracy and as a unitary state is at risk – even if it remains a very flawed example of both.

With hindsight, it may be asked whether the concessions made by the government of Asif Ali Zardari that agreed a military truce and sanctioned the introduction of Sharia law into the Swat Valley were mistaken. Both moves undoubtedly signalled a retreat by the central government. And it was a retreat that has lamentable consequences, not only for the lives of many people, especially women, in the region, but in facilitating the Taliban's advance. No longer threatened closer to home, its forces could move towards Islamabad.

Realistically, though, when the government agreed the truce, it had little choice. Borne to power on the wave of sympathy that followed the assassination of his wife, Benazir Bhutto, Mr Zardari was a weak president from the start. His failure to honour his election promise to reinstate the judges sacked by his predecessor, until he was forced by popular pressure to do so, demonstrated the extent of that weakness. The truce was as much as anything a recognition, however undesirable, of the status quo.

There is little to be optimistic about, when contemplating the immediate prospects for Pakistan – except perhaps in one respect. President Obama has been clear from the start of his presidency that he sees Pakistan as the key to the stability – or, currently, instability – of the region. In appointing the highly experienced and straight-talking diplomat Richard Holbrooke as his special envoy to both Afghanistan and Pakistan, he showed the seriousness of his intentions. During his recent trip to Europe, he also stressed his awareness that military force alone was no answer – in either country. The assistance he has earmarked for Pakistan, particularly for education, was a creditable start.

One difficulty is that, by endorsing continued bombing raids in Pakistan's tribal areas – for the sake of enhancing security in Afghanistan – the Obama administration is at once alienating Pakistanis (not only Taliban sympathisers) and undermining what authority remains to Mr Zardari. This is a contradiction that needs to be addressed.

At least, under this administration, the US has no illusions about the dangers emanating from an unstable Pakistan. In testimony to Congress this week, the Secretary of State Hillary Clinton voiced fears that Pakistan's government was abdicating to the Taliban and the extremists and described the situation as "a mortal threat to the safety of our country and the world". Only by starting from such an unadorned diagnosis, can there be any chance of a solution.