Syria's ability to prevent the guerrillas from attacking Israeli forcesis unclear.
Among the most effective "cards" that Syria has ever played is one that it doesn't fully control: Islamic Hizbullah guerrillas in southern Lebanon, who with Syria's help and Iran's backing are winning their fight against Israel's occupation there.
Syria and Israel are toying with a resumption of peace talks, and any agreement is likely to return the Israeli-occupied Golan Heights to Syria for peace. Linked to that would be an Israeli withdrawal from Lebanon - where Syria keeps its own controlling force of 35,000 troops.
The steady stream of Israeli casualties in southern Lebanon prompted Israeli Prime Minister Ehud Barak during his election campaign last spring to vow an Israeli withdrawal from there, a commitment that was widely applauded in the Jewish state. But Syria's ability to prevent Hizbullah from continuing attacks remains unclear, especially from "rogue" militants.
"Syria has strategic influence over Hizbullah, but not tactical control," says a senior Western diplomat in Damascus. "That tactical control can be taken by those who want to kibosh a peace agreement."
With Syrian acquiescence, Hizbullah has raised the stakes with regular, deeper strikes against Israeli forces and their local, Israeli-trained and supplied South Lebanon Army militia allies. The message to Israel: This front line is still open, and Damascus is the key to solving it.
"The Syrian interest is to keep the Israeli fingers in the mangle, but not to squeeze too hard," says the diplomat.
Israel has occupied parts of Lebanon since 1978, initially to prevent cross-border attacks from Palestinian guerrillas. In 1985 it created a nine-mile strip in the south it calls its "security zone" to thwart Hizbullah, which had taken up the resistance fight.