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.