By Paul Reynolds
World Affairs correspondent, BBC News website
In the immediate aftermath of the bomb which killed the former Lebanese Prime Minister Rafik Hariri and at least nine others, most eyes were turned towards Syria as a possible culprit.
The claim of responsibility could well be a false trail
Then something strange happened - a video claim of responsibility was broadcast on the satellite news network al-Jazeera from an Islamist group saying that Hariri had been killed as a "just punishment" for his close links to Saudi Arabia.
The Saudi royal family of course is one of the main targets of al-Qaeda. Suddenly the equation seemed to have changed.
Had Islamic violence entered current Lebanese politics? That would have repercussions across the region, as Syria also might be in their sights.
President Assad's own father massacred Islamic fundamentalists in his day.
Or was the claim - from an unknown group called Support and Jihad in Greater Syria - a false one?
It could have been, for example, a ploy by whoever planted the bomb to draw suspicion away from themselves, or some fringe elements trying to capitalise on the attack.
We do not know at this stage. What we do know is that anger against Syria has increased in Lebanon recently and was evident again yesterday when opposition leaders virtually accused Syria and the Syrian-backed government in Beirut of responsibility.
What is also likely to happen is renewed pressure by the United States on Syria.
Indeed, the White House spokesman Scott McClellan managed to mention Syria in the very first reaction by the Bush administration to Mr Hariri's death:
Some Lebanese see Syria as a hostile occupying power
"This murder today is a terrible reminder that the Lebanese people must be able to pursue their aspirations and determine their own political future, free from violence, and intimidation and free from Syrian occupation," he said.
The American finger of suspicion was pointing at Syria because Mr Hariri let it be known not long ago that he was in favour of a withdrawal of the 16,000 or so Syrian troops in Lebanon.
These troops have remained despite the end of the civil war. Their supporters say the Syrians stabilise the country. Opponents say they occupy it.
It is an immensely sensitive issue in Lebanon.
The voices of those opposing the Syrian presence were strengthened in September last year when the United Nations Security Council passed resolution 1559 calling for the withdrawal of "all remaining foreign forces" from Lebanon.
The resolution was sponsored by the United States and France, the old colonial power in Lebanon, whose President Chirac was a supporter of Mr Hariri.
This has to be seen in the wider context of US antipathy to the government in Damascus.
In his State of the Union speech this year, President Bush had harsh words for Syria: "We expect the Syrian government to end all support for terror and open the door to freedom," he said.
By "support for terror" Washington means alleged Syrian hospitality to Palestinian militant groups as well as support for Hezbollah which still attacks Israel from southern Lebanon.
Mr Bush has not named Syria as a member of the "axis of evil" - that honour went to Iran, Iraq and North Korea, with Iraq having been retired from the club - but it does appear to be a candidate.
In May last year, Mr Bush banned US exports to Syria apart from food and medicine, stopped Syrian aircraft from flying to and from the United States and froze the assets of Syrians suspected of violating a law passed by the US Congress in November 2003.
This law, the Syrian Accountability and Lebanese Sovereignty Act, declared that its purpose was to "halt Syrian support for terrorism, end its occupation of Lebanon, and stop its development of weapons of mass destruction, and by so doing hold Syria accountable for the serious international security problems it has caused in the Middle East, and for other purposes."
The death of Hariri is sure to have deep repercussions
Another American accusation against Syria is that it has harboured Saddam Hussein supporters who are now fighting against US troops in Iraq.
Syria is still named as a "state sponsor of terrorism" by the State Department.
Syria is seen by the Bush administration as an obstacle to a settlement in the Middle East and as one of those countries in the region which is resisting democratisation.
So there is a long history to this and the death of Mr Hariri will only intensify American hostility.
For its part, Syria regards what happens in Lebanon as part of its own security.
It has announced moves to thin out its forces and move them further east towards its own borders.
The Syrian President Bashar al-Assad said of Mr Hariri's death: "Syria's government and people declare that they stand by brotherly Lebanon in these dangerous situations and extend the warmest condolences to the families of Rafik Hariri and the victims."
He described the apparent assassination as an "odious crime... aimed at striking Lebanese national unity and civil peace".
Syria resents and rejects all the American accusations, regarding itself as a true standard bearer of Arab unity and Palestinian interests.