World powers agreed early Friday to reach a cease-fire in Syria in one week, allowing aid in but giving Russia and the Assad regime time to press an offensive that has expanded the Kremlin’s clout in the region.

The agreement came after more than five hours of talks among the U.S., Russia, Iran, Turkey, Saudi Arabia and other countries, in a meeting that aimed to halt a recent onslaught by Moscow and Damascus that has created tens of thousands of new refugees.

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