The decision by terrorists to strike in London and Glasgow just days after Prime Minister Blair left office is an indication of what may well await America after President Bush leaves office. It’s not an attractive scenario to contemplate, but it’s certainly within the realm of the possible that the Islamist extremists would want to test the will of the next president of America in the same way in which they were apparently testing the will of Prime Minister Brown.

One of the big questions of the presidential campaign ahead is how any of the would-be-leaders of America would respond to such an attempt. Would they blame the policies of their predecessor for provoking the terrorists or for failing to defeat the enemy? Would they pursue a strictly law-enforcement approach or would they react using all the instruments of war? What the attacks in Great Britain show is that these questions are not merely theoretical. Unfortunately, they are likely to be faced by President Bush’s successor.

The positive aspect of such a test, if there can be said to be one, may be that it will become clearer to more Americans that the violence of the terrorists is not directed at a particular administration or its policies but against the West itself and its ideals of liberty and pluralism. Those who think that the terrorist threat will go away with the exit of Mr. Bush or Mr. Blair are mistaken; the terrorists won’t stop until they establish a caliphate of rule by Islamic law across the world, or until they are defeated.