A visitor looks at the faces of some of the victims of the Oklahoma City bombing at the Oklahoma National Memorial museum. Photo by Joe Raedle/Getty Images On 19 April 1995, a truck bomb exploded outside a federal government building in Oklahoma City, killing 168 people, including 19 children. It is still the deadliest domestic terror attack in US history. It was carried out by the white supremacist Timothy McVeigh, who claimed to be avenging the deaths at the Waco siege in Texas exactly two years earlier, in which a confrontation between a religious sect called the Branch Davidians and...