President Donald Trump on Friday posted a confusingly phrased tweet that initially gave the impression he believed the moon was part of Mars.

"NASA should NOT be talking about going to the Moon - We did that 50 years ago," he said. "They should be focused on the much bigger things we are doing, including Mars (of which the Moon is a part)."

NASA officials have said that bolstering a presence on the moon will be an essential step toward conducting further research on Mars.

"Exploration of the Moon and Mars is intertwined," NASA says on a section of its website titled "Moon to Mars."

Shortly before Trump's tweet, NASA's chief financial officer, Jeff DeWitt, went on Fox Business to discuss the agency's initiatives on the moon, including a planned expedition in 2024.

Trump increased NASA's budget to $21.5 billion in fiscal 2019 and has requested another $1.6 billion for fiscal 2020 to help it carry out its 2024 moon mission and future Mars exploration.

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President Donald Trump on Friday posted a confusingly phrased tweet that initially gave the impression he believed the moon was part of Mars.

"For all of the money we are spending, NASA should NOT be talking about going to the Moon - We did that 50 years ago," he said. "They should be focused on the much bigger things we are doing, including Mars (of which the Moon is a part), Defense and Science!"

NASA officials have said that bolstering a presence on the moon will be an essential step toward conducting further research on Mars, CNN's Haley Byrd noted on Twitter.

"Exploration of the Moon and Mars is intertwined," NASA says on a section of its website titled "Moon to Mars Overview."

"The Moon provides an opportunity to test new tools, instruments and equipment that could be used on Mars, including human habitats, life support systems, and technologies and practices that could help us build self-sustaining outposts away from Earth," it adds.

Matt Gertz, a Media Matters senior fellow who closely tracks Fox, pointed out that Trump's tweet came shortly after a segment on Fox Business — one of the news channels Trump frequently watches — in which NASA's chief financial officer, Jeff DeWitt, discussed its initiatives on the moon, including a planned expedition in 2024.

Read more: NASA says it needs a $1.6 billion 'down payment' from Congress to send astronauts back to the moon within 5 years

July 20 will mark the 50th anniversary of the historic Apollo 11 mission, in which the American astronauts Neil Armstrong and Buzz Aldrin became the first people to walk on the moon.

That mission "was what we call 'flags and footprints,'" DeWitt said. "We went, we did walk around, we collected samples, we came back. What we're doing now is enabling a sustainable presence on the lunar surface."

He added: "We still need to drive that innovation and complete those technologies that will allow us to have a sustained presence on Mars. Don't forget: When we go to Mars, you're stuck there for 22 months."

DeWitt said that NASA needed to "prove on the moon that we can have a sustainable presence there first to make sure that it's a safe venture to do." He projected that NASA missions would be going to Mars in the 2030s.

Trump increased NASA's budget to $21.5 billion in fiscal 2019 and has requested another $1.6 billion for fiscal 2020 to help it carry out the 2024 moon mission and future Mars research and exploration.