The National Defense System, an exclusive responsibility of the federal government, coordinated by the Ministry of Defense, and comprising the Army, the Navy and the Air Force. Ruled and monitored by Congress through the Houses' Defense Committees, it is organized on the essential principle of legitimate self-defense: the repelling of any external military aggression in order to guarantee freedom of the people, national sovereignty, and territorial integrity. Its secondary missions include committing to multinational operations within the framework of the United Nations, participating in internal support missions, assisting friendly countries, and establishing a sub-regional defense system.