The United States and Britain have not merely begun a war with Afghanistan's regime. Despite their predictions of a lengthy struggle, they have also begun a deadly race against time. The race for "victory" is lent added impetus by fears that the supporting coalition may fall apart. Yesterday's riots in Pakistan, and unrest in other Muslim and Arab countries, may be only a foretaste of a more fundamental turbulence if the conflict proves protracted and intractable. But of all the time pressures facing Washington and its allies, the daily, upward advancement of Bin Laden towards folk-hero status in the Muslim world is perhaps the most alarming.