Syrian peace talks have been put on hold in Geneva as a Russian-backed offensive has intensified north of Aleppo. U.N. mediator Staffan de Mistura said he hoped talks would resume in three weeks.

Staffan de Mistura: “It is not the end, and it’s not the failure of the talks. Why? They came, and they stayed. Not only, but both sides insisted on the fact that they are interested in having the political process started.”

The peace talks are the first attempt in two years to negotiate an end to Syria’s war that has claimed the lives of nearly 300,000 people and displaced roughly half the country’s population.