The U.N.'s special envoy for Syria says there's just not enough agreement yet to resume peace talks ahead of an Aug. 1 deadline to start a political transition.

Talks between the Syrian government and opposition broke up at the end of April when government forces, backed by Russia, escalated their assault on rebel-held areas.

Staffan de Mistura, speaking to reporters Wednesday following closed consultations with the Security Council, said all sides need to be particularly prepared because of the deadline's fast approach and noted there is a lot of "discrete diplomacy going on behind the scenes."

A truce that brought peace to much of Syria for several weeks largely broke down.