President Donald Trump signed Space Policy Directive 1 on Monday, directing NASA to return Americans to the surface of the moon and onward to Mars.

The order declares NASA must lead U.S. astronauts in "an innovative space exploration program." The announcement continues the White House push to end dependence on Russia for manned launches, which began when the space shuttle program retired six years ago.

"It marks an important step in returning American astronauts to the moon for the first time since 1972 for long-term exploration and use," Trump said during the signing. "This time we will not only plant our flag and leave our footprint. We will establish a foundation for an eventual mission to Mars and, perhaps, someday, to many worlds beyond."

It has been 45 years to the day since Apollo 17 landed, the most recent mission to the moon. Former astronaut Buzz Aldrin noted in a tweet that Apollo 17 was the 6th time humans landed on the moon's surface.

@TheRealBuzz The 6th time humans landed on the moon.

Trump's declaration makes him the third president in the last 30 years to announce a return to the moon. On the 20th anniversary of the first moon landing, Apollo 11, President George H.W. Bush announced the National Space Council of the time would "report back" with "concrete recommendations" to reach "the Moon and Mars and beyond." In 2004, President George W. Bush unveiled a three-step vision for space exploration, saying the U.S. must "return to the moon by 2020."

"With the experience and knowledge gained on the moon we will then be ready to take the next steps of space exploration: human missions to Mars and to worlds beyond," Bush said at NASA's headquarters in 2004.

In October the National Space Council met for the first time since it was disbanded in 1993, led by Vice President Mike Pence, several White House officials and space industry executives.

"America seems to have lost our edge in space," Pence said. "Rather than lead in space, too often we've chosen to drift and, as we learned 60 years ago, when we drift we fall behind."

Boeing and SpaceX, both represented at the council meeting, play key roles in NASA's Commercial Crew program. The government organization selected the two companies to transport crew to the International Space Station, launching from the U.S. Both companies will seek major testing milestones in 2018, with both orbital and crewed flight tests.

Pence said America "will win the 21st century in space." He identified the council as a way to build a coherent vision for U.S. policy and strategy in space.