Russia's envoy to the U.N. on Friday warned long-term ally President Bashar al-Assad over his vow to retake all of Syria, saying he faced dire consequences if he did not comply with Moscow over the peace process. 'Russia has invested very seriously in this crisis, politically, diplomatically and now also militarily,' Vitaly Churkin told Kommersant newspaper, referring to an international agreement to cease hostilities sealed in Munich last week. 'Therefore we would like Assad also to respond to this,' he said, adding that the Syrian leader's stance 'is not in accord with the diplomatic efforts that Russia is making.'