One of the most important jobs of the President of the United States is his constitutional requirement to "take care that the laws be faithfully executed." So not only is a president supposed to shape policy, they are meant to ensure existing laws and the Constitution are upheld. In a way, this makes the president a top-level law enforcer. But, as we outline below, it's not always that simple.
Article II of the Constitution outlines the powers and responsibilities of the President of the United States. It names the president as the head of the Executive Branch as well as Commander-In-Chief of the Army and Navy. It requires the president to provide updates on how the country is doing - known as the State of the Union. Finally, it provides that the president and vice president should be removed from office through impeachment if they commit "Treason, Bribery, or other high Crimes and Misdemeanors."
The main focus of Article II is the Executive Branch - namely, the office of the President of the United States.
Article II names the president as the Commander-In-Chief of the armed forces, gives them the power to make treaties, and puts them in charge of appointing federal officers.
Not exactly. The Constitution says that the president shall "take care that the laws be faithfully executed," not that he must personally enforce the law. Generally, the Attorney General of the United States is considered the nation's chief law enforcement officer.