WASHINGTON -- President Donald Trump has signed the National Defense Authorization Act (NDAA), creating the U.S. Space Force, the sixth branch of the armed forces.

“Space is the world’s newest war-fighting domain. Amid grave threats to our national security, American superiority in space is absolutely vital. And we're leading, but we're not leading by enough. But very shortly, we'll be leading by a lot,” Trump told an audience at Joint Base Andrews in Maryland shortly before signing the NDAA.

The Space Force is the first new armed force since U.S. President Harry Truman created the Air Force in 1947. It is also the largest reorganization of the Defense Department since 1986, when the powers of the chairman of the Joint Chiefs of Staff were increased in an attempt to streamline military decision-making.

The technological changes over the past 70 years since the creation of the Air Force “have transformed the character of space activities,” the Pentagon said in a statement after the signing.

China and Russia have made space a new arena of rivalry “and we are once again doing what is necessary to maintain our competitive edge,” the Pentagon said.

The Space Force will be located within the Air Force and will consolidate the existing space capabilities and associated military and civilian personnel of the other armed forces.

The Space Force will initially start with 16,000 Air Force personnel and be led by Air Force General John Raymond.

The Space Force will be headquartered in the Pentagon and its chief will become a member of the Joint Chiefs of Staff.