paris major western power appear ready showdown russia u.n. security council demand wednesday renewal mandate international inquiry chemical weapons attack syria russian deputy foreign minister sergei ryabkov say wednesday moscow oppose draft u.n. resolution extend mandate investigation unite nations organization prohibition chemical weapons opcw chemical weapons attack syria ryabkov comment come hours russia reject report international inquiry blame syrian government deadly toxic gas attack april 4. joint statement foreign minister britain france germany unite state four countries say full confidence find call syrian regime end use poison gas finally declare opcw chemical weapons possess therefore urge unite nations security council maintain investigative capacity inquiry statement say report security council members common responsibility protect international non-proliferation regime respect previous commitments joint statement say syrian government deny use chemical weapons april attack prompt u.s. missile strike days late syrian air base france warn chemicals attack would meet military response russia key backer syrian government last month cast veto unite nations security council renew investigation mandate inquiry previously find syrian government force responsible three chlorine gas attack 2014 2015 islamic state militants use mustard gas syria agree destroy chemical weapons comply opcw 2013 deal broke russia unite state nerve gas attack kill hundreds people damascus suburbs western countries blame attack syrian government deny message russia western power demand u.n. extend syria toxic gas inquiry