The regime's relations with the United States worsened during 1963, as discontent among South Vietnam's Buddhist majority was simultaneously heightened. In May, in the heavily Buddhist central city of Huế, where Diệm's elder brother was the Catholic Archbishop, the Buddhist majority was prohibited from displaying Buddhist flags during Vesak celebrations commemorating the birth of Gautama Buddha when the government cited a regulation prohibiting the display of non-government flags. A few days earlier, however, white and yellow Catholic papal flags flew at the 25th anniversary commemoration of Ngô Đình Thục's elevation to the rank of bishop. According to Miller, Diệm then proclaimed the flag embargo because he was annoyed with the commemoration for Thục. However, the ban on religious flags led to a protest led by Thích Trí Quang against the government, which was suppressed by Diệm's forces, and unarmed civilians were killed in the clash. Diệm and his supporters blamed the Việt Cộng for the deaths and claimed the protesters were responsible for the violence. Although the provincial chief expressed sorrow for the killings and offered to compensate the victims' families, they resolutely denied that government forces were responsible for the killings and blamed the Viet Cong. According to Diệm, it was the communists who threw a grenade into the crowd.