Much of the money for Pakistan was spent on physical security, like fencing and surveillance systems, and equipment for tracking nuclear material if it left secure areas.

也花费很多财力用于巴基斯坦核武器的物理安全，如隔离和监督系统，以及核原料离开安全区域的跟踪设备。

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But it helps that America has been assisting Russia and others with security upgrades, including better fences, surveillance equipment and radiation monitors, as well as security training, at military and civilian sites where nuclear materials are used or stored.

ECONOMIST: Preventing nuclear trafficking is easier than policing it