Nunn-Lugar Cooperative Threat Reduction Act of 2005

Nunn-Lugar Cooperative Threat Reduction Act of 2005 - Amends the Soviet Nuclear Threat Reduction Act of 1991, the Cooperative Threat Reduction Act of 1993, and the National Defense Authorization Act for Fiscal Year 2000, respectively, to repeal specified restrictions on the use of Cooperative Threat Reduction program (program) funds and activities.

Amends the the National Defense Authorization Act for Fiscal Year 2004 to modify authority to use program funds outside the former Soviet Union, including transferring such authority from the President to the Secretary of Defense.

Directs the Secretary of State to report on each country in which a program is being carried out, including its adherence to arms control and nonproliferation agreements.