Answer: Making and Carrying Out Foreign Policy.
The president is responsible for the foreign policy, for making final decisions.
It includes establishing and maintaining diplomatic relations with other countries and international organizations.
The most significant role is done by the president and your executive branch. They are responsible for making foreign policy ad carrying out. The president can hold summit meetings with world leaders. As commander in chief of the military, the president can, by executive order, rapidly project U.S. power around the globe.