In 1960, Diem and his younger brother and chief political adviser, Ngo Dinh Nhu, accused Durbrow of supporting a failed coup attempt by paratroopers of the Army of the Republic of Vietnam. Durbrow later recalled receiving a phone call from one of Diem's aides, who asked him to tell Diem to surrender or face a howitzer attack on the presidential palace. Durbrow refused, and no attack occurred. He later learned that the aide had been forced to make the call.