The protests were part of the Buddhist crisis, during which the Buddhist majority in South Vietnam campaigned for religious equality after nine people were killed by government forces while defying a ban that prevented them from flying the Buddhist flag on Vesak. The incident prompted the United States to privately threaten to withdraw support for Diệm's government and when the Americans finally reduced aid a few months later, the army took it as a green light for a coup. An inquiry determined that the chemical used in the attack was a liquid component from old French tear gas grenades that had never functioned properly. The findings exonerated the ARVN soldiers from charges that they had used poison or mustard gas. The outcry over the attack had already forced Diệm to appoint a panel of three cabinet ministers to meet with Buddhist leaders for negotiations regarding religious equality. The talks led to the signing of the Joint Communique, but the policy changes it provided were not implemented and widespread protests continued, leading to the assassination of Diệm in a military coup.