The United States Wednesday expressed disappointment over the Philippine government's decision to withdraw its troops from Iraq to gain release of a Filipino truck driver held hostage there. The action came despite high-level U.S. appeals to the Manila government.

The Bush administration is making no attempt to conceal its disappointment over the Philippine decision, and it is pointedly not ruling out the possibility that the hostage episode might harm overall relations between Washington and Manila.

The Philippine government said Wednesday it had begun preparations to withdraw its 51-member military contingent from Iraq in line with the demand of kidnappers who have threatened to kill Filipino hostage Angelo dela Cruz unless the troops left by July 20, a month ahead of schedule.

At a news briefing, State Department spokesman Richard Boucher said U.S. policy has always been that making concessions to hostage takers and terrorists "only encourages that behavior" and he said the Bush administration is disappointed with the Philippine decision.

"We think withdrawal sends the wrong signal, and that it is important for people to stand up to terrorists and not allow them to change our behavior," he said. "We certainly have every sympathy for Mr. dela Cruz. Unfortunately, we have no new information on his status, on his situation right now. But we continue to hold that he needs to be released immediately, and that the terrorists who have captured him need to be caught and punished."

The Philippine withdrawal move came as the Bulgarian government made clear that country's troop contingent in Iraq would remain despite the killing of one of its kidnapped nationals in Iraq and threats to kill a second Bulgarian within 24 hours.

Mr. Boucher said it is up to each government involved to decide how to deal with hostage situations. But he said in other similar cases in Iraq, involving Japan and South Korea, the incidents have only "strengthened the resolve" of countries to stand up to the cruelty and barbarity of the terrorists, which he said "goes against all the world's religions."

Under questioning, the spokesman said "we'll have to see" whether the Manila government's handling of the kidnap case will affect overall relations with the United States.

A senior diplomat who spoke to reporters here said there is no indication that the government of President Gloria Arroyo is changing its broader policy of cooperation with the United States against terrorism, including intelligence sharing and training of Philippine forces dealing with Muslim extremists linked to al-Qaida.

The Philippine decision on its Iraq troops came despite a flurry of high-level contacts with the United States, including a telephone conversation between Mrs. Arroyo and Secretary of State Colin Powell on Sunday.