GENEVA - Syria's government delegation has been 'stonewalling every step of the way' in Geneva peace talks and Washington expects Russia to pressure them to engage seriously in the peace process, a senior US official said on Friday. 'We hope and trust that because the Russians believe in a political solution, a diplomatic solution, they will urge the regime to engage in a serious and constructive way,' the official said. 'The regime hasn't done so yet, that speaks for itself.'