A half-trillion dollar backlog
Data centers have long made some efforts at physical security. But most of these security measures—high fences topped with barbed wire, carefully controlled access, and security cameras—were aimed at preventing espionage or sabotage by a person on the ground, not aerial attacks.，更多细节参见新收录的资料
Science & Environment，详情可参考新收录的资料
Getty Images/BBC，这一点在PDF资料中也有详细论述