For more than 210 years, the Coast Guard has served the nation as one of the five armed forces. Throughout its distinguished history, the Coast Guard has enjoyed a unique relationship with the Navy. By statute, the Coast Guard is an armed force, operating in the joint arena at any time and functioning as a specialized service under the Navy in time of war or when directed by the President. It also has command responsibilities for the U.S. Maritime Defense Zone, countering potential threats to American's coasts, ports, and inland waterways through numerous port-security, harbor-defense, and coastal-warfare operations and exercises.
Today, U.S. national security interests can no longer be defined solely in terms of direct military threats to America and its allies. With the terrorist attacks on September 11, 2001, the U.S. has fully realized the threat faced on the home front from highly sophisticated and covert adversarial groups. The Coast Guard has assumed one of the lead roles in responding to these unscrupulous attacks upon our nation by providing homeland security in our nation’s harbors, ports and along our coastlines. Commercial, tanker, passenger, and merchant vessels have all been subject to increased security measures enforced by the Coast Guard.
The Coast Guard's national defense role to support U.S. military commanders-in-chiefs (CINCs) is more explicitly outlined in a memorandum of agreement signed by the Secretaries of Defense and Transportation in 1995. Four major national-defense missions were assigned to the Coast Guard. These missions--maritime intercept operations, deployed port operations/security and defense, peacetime engagement, and environmental defense operations--are essential military tasks assigned to the Coast Guard as a component of joint and combined forces in peacetime, crisis, and war.
Outside of U.S. coastal waters, the Coast Guard assists foreign naval and
maritime forces through training and joint operations. Many of the world’s
maritime nations have forces that operate principally in the littoral seas
and conduct missions that resemble those of the Coast Guard. And, because
it has such a varied mix of assets and missions, the Coast Guard is a powerful
role model that is in ever-increasing demand abroad. The service’s
close working relations with these nations not only improve mutual cooperation
during specific joint operations in which the Coast Guard is involved but
also support U.S. diplomatic efforts in general: promoting democracy, economic
prosperity, and trust between nations.