The Times' editorial puts it well:
Yet the violence that has claimed at least seventy lives in two days is part of a larger power struggle whose outlines are clear: by destabilising its neighbour, Syria is seeking to force the international community to drop its efforts to hold Damascus to account for the assassination of Rafik Hariri, the former Lebanese Prime Minister, two years ago. This is state-sponsored blackmail. It must not prevail.
But the strategic response, from Beirut and the wider world, must be clear and resolute. Damascus has signalled that in direct talks on regional security it would offer to stanch the flow of would-be suicide bombers into Iraq and the Palestinian territories on condition that it retain a free hand in Lebanon. Talks, in principle, are welcome – but not with blackmailers.