Russia is warning the US there will be a "tough response" if it violates an international treaty barring nuclear weapons in outer space after President Donald Trump ordered the establishment of a "Space Force" as a sixth branch of the US military, Air Force Times reports.

Trump on Monday ordered the Pentagon to establish the space force, which he said would create more jobs and be great for the country's "psyche."

Some members of Congress have already expressed their opposition to Trump's space force. Astronaut Mark Kelly called it a "dumb idea."

Russia is warning the US there will be a "tough response" if it violates an international treaty barring nuclear weapons in outer space after President Donald Trump ordered the establishment of a "space force" as a sixth branch of the US military earlier this week, Air Force Times reports.

Victor Bondarev, head of the Russian Parliament’s Upper House Committee on Defense and Security, on Tuesday said, "If the United States withdraws from the 1967 treaty banning nuclear weapons in outer space, then, of course, not only ours, but also other states, will follow with a tough response aimed at ensuring world security."

Bondarev was seemingly referring to the 1967 Outer Space Treaty.

According to the US State Department, the treaty "contains an undertaking not to place in orbit around the Earth, install on the moon or any other celestial body, or otherwise station in outer space, nuclear or any other weapons of mass destruction."

Bondarev also said the militarization of outer space is a "path to disaster," adding that he hopes "the American political elite still have the remnants of reason and common sense."

Russian Foreign Ministry spokeswoman Maria Zakharova also expressed concern regarding Trump's announcement of the creation of a US space force.

"A military buildup in space, in particular, after the deployment of weapons there, would have destabilizing effects on strategic stability and international security," Zakharova said. She also defended the fact Russia already has a space force, contending it's a "purely defensive" entity.

Trump on Monday directed the Pentagon to establish the space force, which he said would create more jobs and be great for the country's "psyche."

"Our destiny beyond the Earth is not only a matter of national identity, but a matter of national security," Trump said at the White House. "When it comes to defending America it is not enough to merely have an American presence in space. We must have American dominance in space."

In order for a sixth military branch to be created – joining the Army, Navy, Air Force, Marine Corps, and Coast Guard – Congress has to get involved. Some members of Congress have already expressed opposition to Trump's space force and Defense Secretary James Mattis has also exhibited skepticism on the subject.

"At a time when we are trying to integrate the department's joint war-fighting functions, I do not wish to add a separate service that would likely present a narrower and even parochial approach to space operations," Mattis wrote in a letter to Republican Rep. Mike Turner of Ohio last summer.

Mattis has shifted on this somewhat more recently and in May said, "But to look now at the problem, means we have to look afresh at it, and where are the specific problems, break them down, and if an organizational construct has to change, then I'm wide open to it."