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50 U.S. Code § 2573 - International agreements on information on radioactive materials

The Secretary of Energy may, with the concurrence of the Secretary of State and in coordination with the Secretary of Defense, the Secretary of Homeland Security, and the Director of National Intelligence, enter into agreements with countries or international organizations—
to acquire for the materials information program of the Department of Energy validated information on the physical characteristics of radioactive material produced, used, or stored at various locations, in order to facilitate the ability to determine accurately and in a timely manner the source of any components of, or fissile material used or attempted to be used in, a nuclear device or weapon; and
(2) to obtain access to information described in paragraph (1) in the event of—
a nuclear detonation; or
the interdiction or discovery of a nuclear device or weapon or nuclear material.