In an extraordinary turn of events, the attempted assassination of U.S. President Trump at a rally in Pennsylvania has raised questions about security protocols and the actions of the Secret Service. The confrontation between GOP senators and the head of the Secret Service on the floor of the Republican convention was fiery, with senators absolutely furious after learning that the shooter had been identified as suspicious a full 19 minutes before he tried to assassinate the former president. But why was he allowed to take the stage? What led to this security breakdown?