EO's are part of War Powers, to be "Constitutional" Congress must declare a state of war. Five wars have been declared by Congress under their constitutional power to do so: the War of 1812, the Mexican–American War, the Spanish–American War, World War I, and World War II. These declarations were never rescinded so the US has been in a perpetual state of war!
Under Article I, Section 8 of the U.S. Constitution, Congress has sole power "to declare war [and] grant letters of marque and reprisal." But Article II, Section 2 provides that "The president shall be Commander-in-Chief of the Army and Navy of the United States."