Under pressure from Congress, President Bush slapped sanctions on Syria yesterday for supporting terrorism and interfering with U.S. efforts to stabilize Iraq.

The White House said the sanctions include banning U.S. exports to Syria except for food and medicine, prohibiting Syrian aircraft from flying to and from the United States, freezing certain Syrian assets and cutting off relations with a Syrian bank because of money laundering concerns.

Since the Sept. 11, 2001, terrorist attacks, the Bush administration has wavered about how tough its policy should be toward Syria. Some administration officials have been deeply suspicious of Damascus, believing its support of terrorism and development of weapons of mass destruction make it a potential candidate for the "axis of evil" that Bush had said consisted of North Korea, Iran and the former government of Iraq. But others have argued that Syria has been helpful in the war on terrorism, specifically in providing intelligence that helped thwart at least one potential attack.

Indeed, the Bush administration had been unenthusiastic about the Syrian Accountability Act, which was approved five months ago by huge margins in the House and the Senate, and had repeatedly delayed implementing it for fear of adding to tensions in the Middle East. But, facing a deadline next month for choosing from a menu of sanctions, the president finally acted.

"Despite many months of diplomatic efforts to convince the Government of Syria to change its behavior, Syria has not taken significant, concrete steps to address the full range of U.S. concerns," Bush said in a message to Congress. He declared a "national emergency" to address the "unusual and extraordinary threat" posed by Syria.

The United States rarely imposes economic sanctions on other countries because they rile the business community, which yesterday expressed dismay at the administration's actions. The Bush administration last levied sanctions almost a year ago, on Burma.

The practical effect of the new sanctions is mostly symbolic. Diplomatic relations will not be cut, no Syrian flights fly to the United States, and Bush said in his message to Congress that he will waive the sanctions for products such as telecommunications equipment and aircraft parts, in addition to the exemptions for food and medicine.

Thomas Crocker, a partner at Alston & Bird and a sanctions specialist, said the permitted products constitute a large portion of the $200 million in exports from the United States to Syria. Bush justified the continued sale of telecommunications equipment -- such as cellular phones -- as an effort "to promote the free flow of information."

Italy, Germany and France are Syria's biggest trading partners, Crocker said.

Syrian exports to the United States totaled nearly $260 million last year, much of it fuel oil and other petroleum products. While exports from Syria are not barred, U.S. companies may find it difficult to continue working there under the sanctions.

In Damascus, Syrian Prime Minister Mohammed Naji Otari told reporters that the sanctions are "unjust and unjustified," but he said "these sanctions will not have any effect on Syria." He called on Washington to "reverse its decision and not provoke problems between the two countries."

Rep. Eliot L. Engel (D-N.Y.), one of the sponsors of the sanctions law, said the president's action "was a long time coming, but it is better late than never." But, he said, "to me, it's only the beginning," adding that Syria will face even tougher sanctions if its behavior does not change.

In a statement, Bush echoed that sentiment. "The Syrian government must understand that its conduct alone will determine the duration of the sanctions, and the extent to which additional sanctions may be imposed should the Syrian government fail to adopt a more constructive approach to relations with its neighbors, weapons of mass destruction, and terrorism," he said.

Bush, who signed an executive order imposing the sanctions, accused Syria of "supporting terrorism, continuing its occupation of Lebanon, pursuing weapons of mass destruction and missile programs, and undermining United States and international efforts with respect to the stabilization and reconstruction of Iraq."

Last year, U.S. immigration authorities, with the approval of then-acting Attorney General Larry Thompson, authorized the expedited deportation to Syria of Maher Arar, whom they accused of having links with al Qaeda. Arar said that for the 10 months he was in prison, he was beaten, tortured and kept in a grave before he was freed.

A year ago, Secretary of State Colin L. Powell traveled to Damascus and warned Syrian President Bashar Assad that Congress might force the administration's hand if Syria did not take demonstrative steps to act against terrorism and thwart insurgents crossing the Syrian border to fight U.S. troops in Iraq.

U.S. officials have been disappointed with Assad's response. During Powell's visit, Assad said he would close the Damascus offices of extremist Palestinian groups, but U.S. officials said the groups still plot attacks on Israel from Syria.