I do not know, what follows is speculation.
Consider this hypothesis: Rafik Hariri was declared a "collaborator" by the Iraqi Sunni Insurgency, who killed him.
Who stands to gain?, and why?
1. Israel: because it increases US pressure on Syria, and could lead to a weakening of Hizbollah (1) (Jansen, Jordan Times, 17 Feb.),
2. U.S.A.: provides an opportunity to push ahead with the neo-con Middle East Campaign, by increasing pressure on Syria, which the US accuses of aiding the Iraqi (Sunni) Insurgency (3) (Fisk, 16 Feb.)
3. al-Qaeda: striking at a Saudi-linked political power — Hariri had dual Lebanese-Saudi citizenship — with close ties to the West (France) and who was opposed to Hizbollah attacks on Israel (2) (Fisk, 15 Feb.), (5) (Juan Cole 14 & 16 Feb.)
4. Iraqi Sunni Insurgency: to draw Syria further into the Insurgent struggle against the U.S.A. — and Shi’ite electoral power — for the control of Iraq.
A map readily shows how easily one could build pipelines from Iraq through Syria and then Lebanon to the Mediterranean. A shortcut. This natural route is also one we could expect the Insurgent groups tied to the former Saddam Hussein regime (probably the officer corps and the intelligence service) to withdraw along. In Damascus, there must be banks for secreted funds, and refuges in which to regroup, plan, and store munitions. That much Iraqi wealth flowed along this channel in the past only reinforces this logic, which is the basis of US accusations against Syria regarding the Iraqi resistance.
The clarity of this logic would be evident to the Syrians from the start, who would no doubt insist that their Iraqi Insurgent allies not tarry in Syria, so the Washington cops don’t finger Syria as an accomplice. So, hide out in Lebanon.
Think of this exile population, accustomed to power, still possessing wealth, munitions, intelligence capabilities and some connections, as similar in many ways to the anti-Castro Cubans in Miami. Their focus becomes to subvert the power of the government granting them asylum (or cover, perhaps with some blackmail), so as to bring it to bear against their enemies in the homeland. An Iraqi Sunni Insurgency gains if Syria faces the same attack from the U.S. In killing Rafik Hariri, this (hypothetical) exile Insurgency does Syria a "favor" it really doesn’t need, and whose consequences might force Syria to join in the Insurgency, widening the war dramatically.
This hypothesis is like the plot of the Alfred Hitchcock film "Strangers On A Train," in which two men trade murders — initially in jest — so as to free themselves of burdensome restrictions without either being implicated in crime. In the film, one fellow played by Robert Walker actually commits the murder-as-favor he promised, and the second man, played by Farley Granger, is drawn into a perilous struggle to break the blood-bond of murder conspiracy he finds himself in. Syria may be in a similar spot, entrapped by the exile Insurgency and under tightening suspicion by the world’s Top Cop.
There may be no way out for Syria however they respond to the exile Insurgency and the Hariri assassination. The difficulty for them may be that in this case the interests of the U.S., Israel, al Qaeda and the Iraqi Sunni Insurgency all coincide.
Manuel Garcia, Jr. can be reached at: firstname.lastname@example.org
 Michael Jansen, "Who Stands to Gain from Hariri’s Death?," The Jordan Times, 17 Feb. 2005,
 Robert Fisk, "The Killing Of Mister Lebanon," 15 Feb. 2005,
 Robert Fisk, "The Blame For Hariri Hit Falls On Syria," 16 Feb. 2005,
 Robert Fisk, "In Death, Hariri Unites The Lebanese," 17 Feb. 2005,
 Juan Cole, comments of 14 & 16 Feb. 2005