Damascus claims it is merely beefing up border security to prevent smuggling and the infiltration of Islamic extremists from northern Lebanon. But some fear Syria wants to use the threat of Sunni Islamic terrorism as a pretext for reentering Lebanon.
Syria withdrew its troops from its neighbor in 2005 under intense international pressure.
Last month, Syria's president publicly warned that northern Lebanon had become a haven for Sunni militants who aim to destabilize his country. That warning came before back-to-back car bombings in Damascus (Sept. 27, blamed on Sunni extremists) and in northern Lebanon's Tripoli (Sept. 29) that killed at least 22.
Last month the Lebanese Army said Syria had massed nearly 10,000 troops on the border. Syria insists their deployment along the border numbers only in the hundreds.
The National Post, a Canadian daily, reported that Israeli officials are also nervous about Syrian intentions.
The AP noted that Syria-Lebanon ties have actually warmed recently.
The Christian Science Monitor reported last month on worsening sectarian violence in northern Lebanon. There, Sunni Muslim fundamentalists are pitted against a small Shiite group that's close to the Syrian government. Sunni jihadists that oppose the Syrian regime regularly pass between northern Lebanon and Syria, the report said.