President Donald Trump displays the "Space Policy Directive 4" after signing the directive to establish a Space Force as the sixth branch of the Armed Forces in the Oval Office at the White House in Washington, U.S., February 19, 2019.

"America must be fully equipped to defend our vital interests. Our adversaries are training forces and developing technology to undermine our security in space, and they're working very hard at that," Trump told reporters at the White House.

Known as Space Policy Directive 4 (SPD-4), the directive orders the Pentagon draft legislation for Congress that would create the Space Force as a part of the U.S. Air Force. This would establish the first military branch in 72 years. The Air Force is the nation's youngest branch and was added shortly after World War II.

President Donald Trump signed a directive on Tuesday that ordered the Department of Defense create a Space Force as a sixth military branch.

"We're investing in new space capabilities to project military power and safeguard our nation's interests, especially when it comes to safety and defense," Trump added.

The National Space Council developed the directive alongside counterparts at the Pentagon, Joint Chiefs of Staff, Office of the Director of National Intelligence, National Security Council, Office of Management and Budget, and the White House Counsel's Office.

Currently the U.S. Air Force manages the space domain through the U.S. Space Command. This proposed Space Force would stand alongside the Army, Air Force, Navy and Marine Corps. However, the newest branch is expected to be akin to the structure of the Marine Corps, which is a component of the U.S. Department of the Navy but has separate representation on the Joint Chiefs.

The new sister service branch will be represented on the Joint Chiefs of Staff and overseen by an Air Force under secretary for space.

Trump first floated the Space Force idea as a part of his national security strategy March 13. The president described in March how he had originally coined the term as a joke, while discussing U.S. government spending and private investment in space. Trump then directed the Pentagon in June to immediately begin the creation of the new branch.

"I am hereby directing the Department of Defense and Pentagon to immediately begin the process necessary to establish a space force as the sixth branch of the armed forces," Trump said in June before asking Marine Corps Gen. Joseph Dunford, chairman of the Joint Chiefs, to see the directive through.

"Our destiny beyond the Earth is not only a matter of national identity but a matter of national security," Trump said.

In August, Vice President Mike Pence announced the Pentagon's detailed plan for President Donald Trump's vision of a Space Force.

The Pentagon did not immediately respond to a CNBC request for comment.

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