Major powers agreed on Friday to a cessation of hostilities in Syria set to begin in a week and to provide rapid humanitarian access to besieged Syrian towns, but failed to secure a complete cease-fire or an end to Russian bombing.

Following a marathon meeting in Munich aimed at resurrecting peace talks that collapsed last week, the powers, including the United States, Russia and more than a dozen other nations, reaffirmed their commitment to a political transition when conditions on the ground improved.