美安全事件情报分析：孤立袭击还是系统性危机前兆？

1. 核心事实剥离

事件本质：一名嫌疑人从洛杉矶经芝加哥前往华盛顿，4月25日在某活动安检点持枪突破，特勤局特工胸部中弹但防弹衣有效阻挡了伤害。〔SRC:"On 21 April, the suspect left his home in LA by train, travelling to Chicago...On 25 April, he approached a security checkpoint at the event, and 'ran through while holding a long gun'. Secret Service then 'heard