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Layered Nuclear Defense: Exterior Layer

Freight train traveling through snowy mountains. The exterior layer comprises the foreign origin, foreign transit and foreign departure sub-layers. We improve radiological and nuclear material detection abroad through efforts that encourage foreign nations or regions to develop and enhance their nuclear detection architectures.

International engagement fosters bilateral and multi-lateral relationships to enhance strategic architecture development and radiological and nuclear detection capabilities, creating a multi-layered, defense-in-depth approach to combat nuclear terrorism. Emphasis is placed on all pathways and across the U.S. government’s international activities.

The exterior layer covers these matters within or across borders of foreign nations:

  • Maritime modes of transportation within the exterior layer that include public and private vessels over lakes and rivers
  • Air modes of transportation within the exterior layer that include commercial and general aviation
  • Land modes of transportation within the exterior layer that include:
    • public and private automobile traffic
    • railways
    • various types of off-road travel

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