Terrorists who seize and threaten to behead foreign hostages in Iraq have elevated blackmail to a national level. They use the Internet and video cameras instead of pasted-together ransom notes to target the political stability and collective will of entire countries.

By withdrawing its symbolic 51-person force from the U.S.-led coalition -- and then vaunting its surrender as a "triumph" -- the Philippine government gives these technologically innovative extremists a huge success. Manila's withdrawal is militarily insignificant. But it echoes loudly through the psychological and political realms that are the terrorists' most important battlegrounds. Six foreign truck drivers were kidnapped and menaced with execution yesterday.

Some countries -- Italy and South Korea are examples -- have responded to threats that their nationals will be slaughtered on camera by refusing to bargain and renewing their commitments to the coalition of 30-some countries. The contrast between their reactions and those of others -- the Philippines and, in another context, Spain -- to terrorist threats is drawing a new dividing line among nations.

Each of the decisions to hold or to fold is the result of a mosaic of complex motives, judgments and historical associations that are difficult to characterize broadly. But they are not isolated acts.

They carry hints of evolving national character and attitudes toward collective security and national defense. And the decisions to stay or leave will help shape new international alignments that will emerge from the laboratory of counterinsurgency and counterterrorism that Iraq is today.

Durable alliances are held together not by ink on treaties but by the blood that soldiers from different nations shed for a common cause. The sacrifices and hardships that soldiers (and today many civilians) endure together provide anchors for relationships that are inevitably buffeted by the passing diplomatic and political tempests of the day.

World War II did that for the United States and Britain, which have again solidified their "special relationship" in Iraq. The Cold War did the same in different ways for NATO. New anchors will be formed in Iraq as well, even if many governments joined the coalition out of calculation as much as conviction -- that is, even though they may have sent forces to strengthen their political and economic ties with Washington rather than out of a great zeal to be in Iraq.

For the Bush administration, Italy has over the past 15 months been a more reliable and militarily important ally than France or Germany. Italy did not participate in the invasion of Iraq, but it sent a 3,000-strong force to help with the aftermath. The government did not flinch when an Italian hostage was executed on camera and others were threatened this spring. Instead, Rome vowed not to give in to terrorism.

"The Italians are doing important counterinsurgency work in Iraq. Their forces are acquiring experience and knowledge that will be vital in the long conflict against global terrorism that lies ahead," one senior U.S. policymaker told me recently.

"Italy today is occupying the space that France once held in terms of projecting military force abroad from the European continent," adds another senior U.S. official. "Any American president who is serious about the war against terrorism would see it that way."

That sentiment was expressed in concrete form when attempts were made recently to revive the secretive four-power meetings known as "the quad," which brought together Britain, France, Germany and the United States for high-level diplomatic discussions during the Cold War and afterward.

The quad meetings were never officially acknowledged, to minimize the indignation of Canada and other NATO allies -- especially Italy -- that felt excluded. Last week the White House told foreign diplomats that it had no intention of bringing the quad back to life. Unless that decision is reversed by a future administration, France and Germany have lost a privileged if informal perch in alliance management.

This action is not, and should not be, intended as American retaliation against friendly nations. Those countries have every right to interpret and pursue their national interests as they see fit. The same is true for President Gloria Macapagal Arroyo, who agreed to accelerate the Philippines' withdrawal from Iraq to win the liberation of a Filipino hostage Tuesday. She compounded the ignominy of her decision by calling the terrorist-induced swap "a time of triumph."

But it will not be surprising if Americans come to their own judgment that coalition members that have shown political solidarity and maturity in resisting terrorism in Iraq -- Japan, Bulgaria, Poland and others belong on that list -- have forged new bonds of alliance with the United States that will count for much in the international hierarchy of interests and friends.