Claimed video of Syrian troops joining demonstrators in Al-Bukamal on Saturday (see 0440 GMT)
1929 GMT: Activists are reporting that security forces have used live gunfire against protesters in Daraa, Barza (southwest of Jisr al-Shughour), and in the LCCS is reporting that armed cars, driven by secret police (Shabiha) have opened fire in Homs:
"Cars belonging to armed shabiha roam the besieged neighborhoods and open arbitrary gunfire especially in Bayada & Khaldieh districts, gunfire from checkpoint present at Zenoubia School in Khaldieh"
1922 GMT: An activist has posted these graphic pictures, claiming to show casualties in Sana'a today.
1913 GMT: An in Sana'a, violence has broken out. There are reports of deaths, including a family of five. According to Reuters:
Fighting between government forces and opposition supporters erupted in Yemen's capital Sanaa on Monday, killing six people, opposition sources said. The fighting was the first to break out in Sanaa since President Ali Abdullah Saleh flew to Saudi Arabia for treatment after sustaining severe burn wounds when an attempt to assassinate him was made in June....
One clash began when demonstrators seeking to increase pressure on Saleh to quit marched outside a square where they have been camped for months, said the sources, who declined to be identified.
'Hundreds of youths marched out of the sit-in area, but were confronted by security forces and gunmen in civilian clothes who fired on them. They killed one protester and wounded eight others,' said one source.
In northern Sanaa, a family of five was killed by shelling during clashes between Republican Guard forces and pro-opposition tribesmen, opposition and tribal sources said.
1905 GMT: We've often spoken of the 3 fronts in Yemen, protesters v. Saleh, tribes v. Saleh, and the Yemeni government v. radical muslim insurgents, including members of Al Qaeda. As if the situation there could get any more complicated...