Elon Musk is challenging President Donald Trump's new NASA bill, saying it does nothing to boost his private company's mission to Mars. The SpaceX CEO has a big stake in the game -- he's spent a large amount of time and money trying to get humans to the Red Planet.

"This bill changes almost nothing about what NASA is doing. Existing programs stay in place and there is no added funding for Mars," Musk tweeted Tuesday after Trump signed the bill. "Perhaps there will be some future bill that makes a difference for Mars, but this is not it."

On Tuesday, Trump signed a $19.5 billion appropriations bill that mandated NASA to pursue human exploration of Mars by the 2030s. CNET reports that this is the space agency's largest operating budget to focus on "core missions in space science, space technology, aeronautics, human space flight and exploration, and education."

But Musk thinks that isn't enough to make commercial travel to Mars a reality for the public. SpaceX is collaborating with NASA, under a $1.6 billion contract, and has flown 10 cargo missions to the International Space Station. The ultimate goal of SpaceX is to colonize Mars.

This isn't the first time Musk has disagreed with the president. The billionaire entrepreneur is on Trump's business council and, despite conflicting opinions on immigration and climate change, remains there to try to influence Trump. After a meeting in February, Musk tweeted that leaving and not voicing his views would be wrong.