Russia’s foreign minister says a ceasefire is to take effect in Syria within a week, urging the Saudi-backed opposition to abandon its “unconstructive” stance and return to the negotiating table without preconditions. “I hope that the opposition and those who control various groups of opposition will have no more reasons to somehow avoid meeting their obligations,” Sergei Lavrov said on Friday. He made the announcement during a press conference after marathon talks among members of the...