Syrian Republican Guard trucks equipped with machine guns and carrying soldiers in combat gear patrolled the circular road around Damascus ahead of prayers on Friday, a witness told Reuters.
Two other witnesses said various security units and secret police manned checkpoints around Damascus, cutting off the city from the suburbs and rural regions, as telecommunications and electricity were cut off from urban centres and towns that had defied warnings not to be the scene of anti-government protests.
Republican Guards deployed in the suburb of Douma earlier this week and Assad sent the Fourth Mechanised Division under the command of his feared brother Maher to hit the city of Deraa, the cradle of the democratic uprising against his 11 year autocratic rule.
A senior Western diplomat that despite army deployments, protests could still erupt across Syria after Friday prayers, the only occasion Syrians are allowed to gather en masse.
"If the protests turn out to be large, and I suspect that they will be, it will be another setback for the regime, which sent the army to the cities for the sole purpose of subduing the people," the diplomat said.
"The regime is already disappointed with how the military campaign is going. Deraa is resisting."