President Donald Trump's administration on Thursday announced a plan to create a Space Force as a sixth branch of the U.S. military by 2020.

The plan, unveiled by Vice President Mike Pence, is intended to strengthen American power in space against the growing capabilities of adversaries such as Russia and China.

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"Today, other nations are seeking to disrupt our space-based systems and challenge American supremacy in space as never before," Pence said in an address at the Pentagon. "Our adversaries have transformed space into a warfighting domain already."

Pence said that while other countries increasingly possess the capability to operate in space, "not all of them share our commitment to freedom, to private property, and the rule of law," in a veiled criticism of space programs by Russia, China, North Korea and Iran.

"As we continue to carry American leadership in space, so also will we carry America's commitment to freedom into this new frontier," he said.

Pence said the administration will work with Congress on the plan and will outline a budget next year.

The administration renewed Trump's call on Congress to invest an additional $8 billion in the nation's space security systems over the next five years, according to the vice president.