At the highest levels. It would be interesting to know how this report relates to [1] this one. From the [2] Jerusalem Post, with thanks to Doc Washburn:

Officials at the highest levels in Syria and Lebanon organized the assassination of former Lebanese prime minister Rafik Hariri, according to the Kuwaiti newspaper a-Siasa.

The report revealed that two high-ranking Syrian generals – including Syrian president Bashar Assad's brother-in-law, Brig. Gen. Asef Shawkat, whom he appointed Friday to head military intelligence – and a Lebanese general.

The newspaper did not reveal the sources of the report.

The Lebanese and Syrian governments have denied any role in the death of Hariri, who was killed by a massive bomb as he was driven in his motorcade through central Beirut. The blast killed 16 other people and wounded more than 100.

The murder of Hariri, a politician who was seen as a key figure in applying international pressures to effect Syrian withdrawal from Lebanon, was evidently intended as a bloody warning to the Lebanese to think twice before demanding that Syrian troops pull out, the report commented.