THE BUSH administration rightly reacted quickly to a report by the United Nations that compellingly links the Syrian government to the assassination of former Lebanese prime minister Rafiq Hariri. President Bush said yesterday the U.N. Security Council should convene "as quickly as possible" to respond to the investigation; the United States and France are reportedly discussing two resolutions that would demand accountability from the government of Bashar Assad.

The United States has plenty of reasons of its own to bring pressure on Mr. Assad, including his support for foreign terrorists and Sunni insurgents in Iraq. But the detailed report compiled by the U.N. commission clearly justifies -- indeed, makes urgent -- Security Council action. Citing multiple witnesses, documents and recordings of conversations, the investigation details both Syria's dispute with Mr. Hariri and the likely involvement of a number of senior officials in plotting his murder. It also reports the systematic stonewalling of the probe by the Syrian government.

By insisting on full Syrian cooperation with the ongoing investigation, the Security Council has a rare opportunity to enforce consequences for a state-sponsored act of political murder. The Middle East has been poisoned by such acts for decades, yet almost never have the killers and their sponsors been identified and brought to justice. No regime merits such action more than the government of Mr. Assad, who since the fall of Saddam Hussein has stood out as the most conspicuous sponsor of terrorism in the Middle East. In addition to brazen meddling in Iraq and in Lebanon, where bombings and assassinations linked to Damascus have continued in the months after Mr. Hariri's Feb. 14 slaying, Mr. Assad is a prime sponsor of terrorism against Israel.

Another U.N. report next week is expected to link his government to the support of Hezbollah and infiltration of weapons and extremists into Palestinian refugee camps in Lebanon.

Some apologists have argued that Mr. Assad, who succeeded his father as Syria's dictator in 2000, is the victim of hard-liners in his government. The U.N. investigation showed otherwise. Chief investigator Detlev Mehlis of Germany compiled multiple accounts of a meeting on Aug. 26, 2004, between Mr. Assad and Mr. Hariri, in which Mr. Assad threatened to "break Lebanon over your head" if the prime minister did not go along with the illegal extension of the mandate of the Lebanese president, a Syrian puppet. Another Syrian witness told the investigation that the decision to murder Mr. Hariri was made at a later meeting attended by Mr. Assad's brother, Maher Assad, and his brother-in-law, Major Gen. Asef Shawkat.

Also directly implicated is Gen. Rustum Ghazali, Syria's most recent intelligence chief in Lebanon, and its former ambassador in Washington, Walid Mouallem. Mr. Mehlis has compromising tape recordings of both of them, including a meeting in which Mr. Mouallem warned Mr. Hariri, two weeks before his death, that "we and the [security] services here have put you into a corner." Intriguingly, one senior official not implicated in the murder plot is Interior Minister Ghazi Kanaan, who was found in his office last week, dead of a gunshot wound, in what officials said was a suicide.

The Security Council has a good precedent to follow here. When Western investigators linked the Libyan government to the 1988 bombing of a Pan Am airliner over Scotland, the United Nations applied sanctions to the regime of Moammar Gaddafi and kept them in place until his government accepted responsibility for the crime and surrendered two of its authors for trial. The United Nations should demand no less in this case. The Syrian sponsors of Mr. Hariri's murder must be identified and brought to justice; if that includes Mr. Assad and his relatives, so be it.