While the US steps up its efforts to cut off terrorist finances and destroy their bases, more than 5m people in Afghanistan facean increasing danger of starvation.

The prospect of military intervention has forced aid agencies to withdraw their staff from the country. The closure of its borders has blocked the inflow of 20,000 tonnes a month of grain. This was the aid that the United Nations World Food Programme had been directing to 3.8m Afghans. From November the UN estimated that 5.5m - a quarter of the population - would need aid.

Even the distribution of existing stockpiles of grain is being obstructed by the Taliban, the ruthless and bigoted regime that controls most of the country.

The Taliban's latest threat to hang anyone using satellite or wireless communications makes aid work almost impossible. There are no other telecommunications in most parts of the country.

This crisis presents George W. Bush with a challenge. The US president has said that his country's war against terrorists and those who harbour them is not intended to harm peaceable Muslims.

If he attacks the Taliban as part of an effort to capture Osama bin Laden and put him on trial for terrorist atrocities, there is a high probability that vital food aid would continue to be blocked.

This should not be dismissed as "collateral damage". It could well prove a humanitarian disaster on a vast scale. Those in danger include many who hate the Taliban and who are well disposed to the US, the largest single provider of aid up to now.

In planning its strike against terrorists the US must therefore think simultaneously of ways to resume the supply of food, particularly in the north and west where starvation is most imminent.

There are formidable difficulties. For a start, air lifts would probably be needed into a hostile country. But a determined effort to avert starvation could do much to improve the US's credit in the Middle East and central Asia.

If, on the other hand, large numbers of Afghans were left to die, there would be no shortage of people to blame the US and its allies, however unjustly.

It may well prove necessary to remove the Taliban and its fanatical adherents by force. Not only does the regime shelter terrorist groups; it has piled misery on to desperate poverty for Afghans.

But a military victory would not be enough. The US must also win a global war for hearts and minds. If the first wave of allied aircraft over Afghanistan carried food, not bombs, Mr Bush might claim a resounding moral victory. That would strengthen his alliance in the broader battles against terrorism.