The unmasking in the United Kingdom of a plot to blow up 10 U.S. airliners is a clear reminder that a serious threat is still out there.

The targets were flights of American, Continental and United airlines from London bound for the United States. If the plot had succeeded, the death toll apparently could have approached the number killed in the 9/11 attacks. Fortunately, prompt British action seems to have crushed the effort in its nest. At least 24 arrests have been made.

There is already considerable impact, in the United States as well as in the United Kingdom. The first came yesterday in the form of increased security measures that all air travelers will face. No liquid or gel products in carry-on luggage will be the first point of pain. No bottled water, juice or other drinks may be carried on to the plane. Items like perfume, shaving cream and hair care products must be stowed in checked luggage, which airlines sometimes deliver late or lose.

A second "knock-on" result is already appearing in the United Kingdom as the British increasingly come to question the price they are paying for Prime Minister Tony Blair's support of the United States militarily in Afghanistan and Iraq and with respect to Israeli actions in Lebanon. The United Kingdom provides transit facilities for U.S. deliveries of bombs to the Israeli Defense Forces, for example.

Polls show that a growing proportion of the British population doesn't like these policies in their own right. To the degree that they see the United Kingdom possibly targeted for the policies by terrorists, and to the degree that they feel the inconveniences caused by reactive security measures drilling into their own lives -- particularly during their traditional August vacation time -- the more the British will turn against Mr. Blair's position and call for policy change and his early departure.

This is, of course, the terrorists' intention in plotting the attacks -- to drive a wedge between the United States and the United Kingdom and to further isolate the United States. But how far can America expect Great Britain to go along this path as the price rises for its people, not to mention for domestic travelers in the United States and the American airline industry?

Isn't this another argument for getting an immediate cease-fire in place and the Middle East peace process relaunched? Such action wouldn't be giving in to terrorists; it would be aligning U.S. foreign policy to the best interests of Americans at home and of America's best ally abroad.