KYIV, Ukraine (AP) — Clinching a deal to end the Russia-Ukraine war “is far too complex to be done quickly,” a senior Kremlin official said Wednesday, as the U.S. labors to bring momentum to peace efforts and expresses frustration over the slow progress.

President Vladimir Putin is open to peace in Ukraine and intense work is going on with the United States, but the conflict is so complicated that the rapid progress that Washington wants is difficult to achieve,