John Kerry threatens Russia with serious sanctions over Ukraine

US secretary of state condemns Russia’s ‘extraordinarily craven behaviour’ after ceasefire left in tatters despite prisoner exchangeThe US has warned it could level “serious sanctions” on Russia within days over breaches of Ukraine’s truce, which is in tatters despite pro-Moscow rebels and government forces exchanging scores of prisoners. A separatist official said 139 Ukrainian troops and 52 rebels had been exchanged at a remote frontline location near the village of Zholobok, 12 mi