So much for hashing things out. The U.S., siding with rebels, and Russia, allied with Bashar Assad, failed to reach an agreement in Syria this week to prop up a collapsed truce. Now the country is being subjected to a regime-led push to retake rebel-held areas. Assad’s warplanes are pounding Aleppo, where human rights activists say scores have died and where centers set up to help victims are reportedly being hit. American and Russian officials pointing fingers and getting nowhere will only add to the trouble — and to hard feelings on both sides.