Trump reaches back to 2016 campaign to slam Clinton over Mars

It's been more than a year since the 2016 election. But Trump said that his space plan was more fulsome than Clinton's, even though the former secretary of state said during her campaign that she would like to make "human exploration of Mars a reality."

"You wouldn't be going to Mars if my opponent won," Trump claimed on Tuesday. "You wouldn't even be thinking about it."

The comments came during a speech before military members in California, where Trump was making his first trip to the state as President. He visited the US-Mexico border earlier in the day to tout his border wall plan.

Late last year, Trump directed NASA's acting administrator, Robert M. Lightfoot Jr., to "lead an innovative space exploration program to send American astronauts back to the moon, and eventually Mars" during a White House signing ceremony in December.

"The directive I am signing today will refocus America's space program on human exploration and discovery," Trump had said. "It marks an important step in returning American astronauts to the moon for the first time since 1972 for long-term exploration and use. This time we will not only plant our flag and leave our footprint."

Trump's attack ignores the fact that Clinton did want to explore Mars.

"A goal of my administration will be to expand this knowledge even further and advance our ability to make human exploration of Mars a reality," Clinton said in response to a questionnaire on science policy from ScienceDebate.org.

Trump has remained fixated on Clinton throughout his time as president, even though he defeated her more than a year ago.

Trump, later in the speech, said he would treat space as a military domain and would like to create a "space force."

"Space is a war-fighting domain, just like the land, air and sea," Trump said. "We may even have a space force."