Investigators are still picking through the burnt rooms of the Marriott Hotel in Islamabad but all attention is properly on the tribal areas on the western border of Pakistan, where the prime suspects behind the suicide blast are believed to be.

Yesterday gunmen also kidnapped a senior Afghan diplomat based in Peshawar. Meanwhile, the new Pakistani Government was struggling to counter reports of American aerial attacks across the border in pursuit of Pakistan-based Taleban.

These events are linked. The threat of terrorism, to which Asif Ali Zardari, the President, referred hours before the Marriott blast, is now located most solidly in the barely regulated tribal areas, which count as part of Pakistan but are not under government control.

Attacks have spread into the margins of the North West Frontier Province next to the tribal areas.

This is, as Zardari said, one of the greatest problems that Pakistan now faces. The terrorism illustrates one of the worst problems neglected in the 61-year history of Pakistan: its lack of clear borders to the east (Kashmir) or the west (the Durand line between the tribal areas and Afghanistan).

That is the legacy of partition from India. But Pakistan's leaders have also found the ambiguity too much help as a distraction, allowing them to focus radical instincts on these endless disputes rather than on failings at home.

In attempts by other countries to help Pakistan to emerge from its current crisis, one goal, however difficult, should be clear borders.

The Marriott bombing gives Zardari a difficult challenge: does he want to pursue the Taleban based in western Pakistan or not? There is one easy choice embedded within that: to protest against the US military action across the Afghan border, which has been a feature of the past few months. The US should acknowledge that this action is extravagantly inflammatory and stop it.

The strikes feed the reflexive anti-US feeling that has a much wider natural constituency in Pakistan than militant Islam, but which can easily be used by the religious extremists. Even the most urbane of Pakistani diplomats have been giving warning of the dangers of the US taking Pakistan's consent for granted.

Behind that issue, however, is the more complicated one of whether to strike a deal with the Taleban in Pakistan or pursue it with force. President Musharraf, after wavering, came down on the side of military action at great cost to the army and to his own position.

This is a delicate discussion for the US and Britain to hold with Zardari and Pakistani army chiefs. They cannot expect that Pakistan's leaders will throw their weight behind an operation that could be so destabilising to the border without considerable incentive.

There are already many in the Pakistani Parliament who argue that it is worth doing deals with tribal leaders — even if that means that efforts by the US and Britain in Afghanistan are futile — to preserve peace in Pakistan.

The billions of dollars in aid, which the US and Britain have recommitted to the new Government, are one incentive. But so is the Marriott bomb.

It shows that terrorism is a threat to the integrity of the whole country. So is the haziness of the borders. Other countries can argue to Zardari that of all the ways in which Pakistan fails to resemble a normal country, the uncertainty about where its rule ends is one of the most damaging.

The most encouraging aspect of the Marriott bomb is that Zardari, in the speech just beforehand, seemed to agree.

Times Recommends

• Heed the great stabiliser’s words
• How a voice for everyone led to stalemate
• Bakara market becomes a slaughterhouse