A cardinal principle of diplomacy is never to allow frustration over failed negotiations to prevent their eventual resumption.
US Secretary of State John Kerry now appears to have done this overnight following collapse on 19 September of the Aleppo ceasefire he had painstakingly negotiated with Russian Foreign Minister Sergei Lavrov.
The overnight rupture followed a last-ditch attempt to revive negotiations in a phone conversation between the two over the weekend.
This effort may have become ca