The U.S. Department of Defense is increasing its preparation for various international security threats, including a possible collapse of North Korea's communist regime.

The Washington-based Center for Strategic and International Studies (CSIS) said the department is preparing to conduct a legally mandated review, which takes place every four years, on international security.

The 2010 Quadrennial Defense Review (QDR) analyzes various scenarios of security threats. It will be provided to the U.S. Congress early next year. Led by Under Secretary of Defense for Policy Michèle Flournoy, five issues teams will examine a series of scenarios to analyze current and future challenges as a means to develop new policies.

Issue Team 1 will analyze scenarios revolving around operations in Iraq and in Afghanistan, regime collapse in North Korea and a potential loss of control of nuclear weapons in Pakistan.

Issue Team 2 will analyze the possibility of Iran going nuclear, Issue Team 3 will focus on homeland defense, and Issue Team 4 will work on recalibrating U.S. military presence around the world.

Issue Team 5 will discuss improving the department’s efficiency and effectiveness.