WASHINGTON, D.C. – If a U.S. led screening plan for weapons of mass destruction isn’t implemented at Canadian ports, there could be a crippling shutdown according to the head of U.S. Customs.

The U.S. is acting on concerns that terrorist groups may be planning an attack that would see a nuclear device shipped to an American port and then detonated, killing thousands of people. The result would shut down ports around the world, according to Robert Bonner.

“Halifax, to use a Canadian example, what happens if that port gets shut down? The economies of those areas are dependent upon containers, ships coming in, being off-loaded and moved. I mean, I think there’s an interest there in not having the system shut down,” says Bonner.