Nuclear Weapons Threat Reduction Act of 2007 - Authorizes the President, upon a specified congressional certification by the Secretary of State, to make voluntary contributions for creation of a low enriched uranium reserve administered by the International Atomic Energy Agency (IAEA) that would help guarantee the availability of fuel for commercial nuclear reactors and dissuade countries from building their own uranium enrichment capability.

Authorizes appropriations for voluntary contributions to the IAEA.

Directs the National Academy of Sciences to report to Congress on a verification regime for a fissile material cutoff treaty.

Directs the President to report to Congress respecting: (1) a plan to ensure the security of all nuclear weapons and weapons usable material at vulnerable sites worldwide and for working with other countries to ensure such materials' security; and (2) U.S. strategy and policies regarding the 2010 Nuclear Non-Proliferation Treaty Review Conference.

Authorizes appropriations to establish a national technical forensics program to develop technologies and procedures for determining the origin of nuclear materials, whether seized intact or collected after the detonation of a nuclear bomb.

Establishes the Commission on United States Objectives and Strategy for Nuclear Nonproliferation and Peaceful Use of Nuclear Technology.