What Are the Responsibilities of the Department of Defense?

The United States Department Defense is tasked with the responsibility of keeping the United States safe and secure. However, the actions that go into such a sweeping duty are many. Every branch of the military except the Coast Guard reports to the Department of Defense, which in 2010 was led by Dr. Robert M. Gates. Gates is the 22nd secretary of defense and is the only secretary in U.S. history to remain in the top defense position through two presidents. He was sworn in in late 2006, and President Barack Obama asked Gates to continue his tenure.

As the oldest and largest governmental organization, the U.S. Department of Defense oversees a vast military. There are more than 1.3 million men and women serving on active duty, about 684,000 working in as civilian personnel and about 1.1 million serving in the National Guard and Reserve units as of 2010, according to the official Department of Defense website. The Department of Defense also helps provide for more than 2 million military retirees and family members through governmental benefits.

The U.S. Department of Defense is set up to defend the United States during times of war and is tasked with keeping the country secure and free from threats.

The Department of Defense does send U.S. troops to conflict areas throughout the world to both help other nations fight wars and to maintain peace post-conflict.

The U.S. Department of Defense deploys National Guard and Reserve units during domestic disasters, such as hurricanes and floods. These troops help with peacekeeping and humanitarian aid.

The president of the United States is the commander-in-chief of the armed forces and the "ultimate authority," according to the official Department of Defense website. The Secretary of Defense works with the military departments, the Chairman of the Joint Chiefs of Staff and the other command leaders to carry out defense policy. The organizational flow, according to the Department of Defense, is as follows: "The departments train the forces, the Chairman of the Joint Chiefs of Staff plan the military operations, and the unified commands carry out the plans."