In a stunning turn of events, the director of the Secret Service, Kimberly Cheadle, stepped down amidst a catastrophic failure of security. Just ten days prior, a gunman had managed to infiltrate a rooftops, coming perilously close to assassinating a former president despite a robust security presence. Cheadle's拒绝 to resign until Monday in the face of bipartisan calls highlights the gravity of the situation.