Elon Musk is the founder-CEO of rocket company SpaceX.But Musk isn't privy to all of SpaceX's classified work with the US government, per the WSJ.Musk obtained top-secret clearance in 2022.SpaceX CEO Elon Musk's security clearance doesn't grant him complete access to the company's classified work with the US government.Musk isn't allowed to enter SpaceX facilities where classified information is being deliberated upon, The Wall Street Journal reported on Sunday, citing people familiar with the matter.The billionaire also isn't privy to the classified cargo SpaceX launches into space as part of the company's contracts with US national security agencies, per the outlet.In October, Musk said at a Trump campaign event in Pennsylvania that he has "top-secret clearance" for his work at SpaceX.Musk obtained his top-secret clearance in 2022, following a review process that took years, the Journal reported. SpaceX's lawyers had advised the company not to seek a higher security clearance for Musk because he would have to disclose details about his drug use and interactions with foreign nationals.In 2018, Musk appeared to smoke a joint during an interview with Joe Rogan. Musk later said in an interview with "60 Minutes" that he had "no idea how to smoke pot."When the Journal reported about Musk's drug use in January, he said that "not even trace quantities were found of any drugs or alcohol" in his system when NASA requested that he undergo three years of random drug testing.As for interactions with foreign nationals, Musk's business dealings have seen him meet with various foreign leaders over the years.In April, Musk visited China, where he met with Premier Li Qiang, the country's second-highest-ranking politician. The two discussed the roll-out of Tesla's self-driving technology in China.In October, the Journal reported that Musk has been in regular contact with Russian President Vladimir Putin since late 2022. In a statement, SpaceX said the Journal's story was "incredibly misleading" and based on "completely unsubstantiated claims."Musk and Trump's relationship grows closerMusk's clearance status might no longer be a problem for him, given his close relationship with President-elect Donald Trump.Musk endorsed Trump and spent at least $119 billion on his campaign. In the past weeks, he has reportedlyjoined Trump on calls with world leaders,including Ukrainian President Volodymyr Zelenskyy.In November, Trump announced Musk as the co-lead of the Department of Government Efficiency, or DOGE. The SpaceX and Tesla CEO will lead the commission alongside Vivek Ramaswamy.Musk and Ramaswamy have talked about significantly reducing the size of the federal workforce and shutting down entire government agencies like the Department of Education and the Consumer Financial Protection Bureau.Musk founded SpaceX in 2002. It was valued at about $350 billion during the latest round of staff share purchases. Musk is currently worth an estimated $455 billion, per the Bloomberg Billionaires Index, making him the richest person in the world by a roughly $200 billion margin.Representatives for Musk at SpaceX and the Defense Department did not respond to requests for comment from Business Insider.