The United States and Russia have agreed to call for an international investigation of the deadly chemical weapons attack in Syria last week. The joint bid for the United Nations and weapons experts to investigate the sarin gas attack came after US Secretary of State Rex Tillerson met in Moscow for talks with Russian Foreign Minister Sergei Lavrov, and later with President Vladimir Putin.<br/><br/> The dispute between Moscow and Washington involves how the April 4 chemical weapons attack in Syria occurred. The chemical attack on rebel-held Khan Sheikhun had killed more than 85 people and sickened hundreds others. Mr Tillerson said, the U.S. is quite confident that it was planned and executed by Syrian regime forces. <br/><br/>But Mr Lavrov said, both Syrian Government and Russian military repeatedly handed evidence to the Organization for the Prohibition of Chemical Weapons (OPCW) that chemical weapons had not been used in Syria.<br/>The chemical attack had prompted U.S. President Donald Trump to launch a retaliatory missile strike against the regime of Syrian President Bashar al-Assad.