Western officials, such as British Ambassador Mark Lyall Grant, had expressed concerns about the completeness of Syria's disclosures, and said the OPCW mission should remain in place following removal of chemical weapons until verification tasks can be completed. A late disclosure in 2014 regarding Syria's ricin program raised doubts about completeness of the government's declaration of its chemical weapons stockpile, and in early May 2015, OPCW announced that inspectors had found traces of sarin and VX nerve agent at a military research site in Syria that had not been declared previously by the Assad regime. Syria appeared to bomb Khan Shaykhun with sarin in April 2017. A chemical attack on Douma on 7 April 2018 that killed at least 49 civilians and injured scores more has been blamed on the Assad government, though the Syrian government disputes these charges.