Jihadi militants in Syria including al-Qaida are mobilizing again for all-out war against President Bashar Assad, taking advantage of the collapse of peace talks to eclipse nationalist rival insurgents that signed on to a faltering truce.

Al-Qaida's Syrian branch, the Nusra Front, was excluded from a cease-fire put in place in February and from peace talks that followed. The talks broke up last month, with Assad's government and its foes blaming each other for military escalation.

After lying low in the early days of the truce, Nusra has re-emerged on the battlefield as the diplomacy has unraveled, spearheading recent attacks on pro-government Iranian militias near Aleppo, Nusra commanders and other rebels say.