The billionaire was filmed on the popular show ‘The Joe Rogan Experience’ sharing a joint and a glass of whiskey with the host in September last year, during the two-and-a-half hour broadcast. The US Government is now reviewing Mr Musk’s security clearance, which grants access to classified government information. According to a Pentagon official, the incident report was started some time after the event.
The SpaceX chief executive has a security clearance as the company provides satellite launch services to the US government.
If Mr Musk loses his security clearing it could impact his work with Nasa.
SpaceX is working in partnership with Nasa for missions to the International Space Station.
Nasa also awarded SpaceX a contract to develop the Dragon craft which became the first commercial spacecraft designed for astronauts to dock in the ISS.
It will return to Earth today after its test mission last week.
The US Department of Defence stated it would be “following its normal process” when investigating the incident.
In a statement it said: “The Department of Defence is following its normal process when information which may affect an individual’s clearance eligibility is brought to our attention.”
Meanwhile Lieutenant Colonel Mike Andrews, a Pentagon spokesman said: “For privacy and security reasons, we do not publicly discuss individual clearance status.”
According to a Bloomberg report, Mr Musk has refiled for his SF-86 security form.
It requires a federal employee or contractor seeking a clearance to acknowledge any illegal drug use over the previous seven years.
Although cannabis is legal for recreational use in many states, including California, but it remains illegal for federal employees or contractors with security clearances.
Meanwhile a SpaceX official said the review has not had an impact on the company.
SpaceX founded in 2002, is currently on the verge of completing one its most daring missions as its SpaceX Crew Dragon is set to leave the International Space Station.
Launched just under a week ago, on March 2 , the commercial astronaut capsule created history when it was remotely docked into the space station.
The crew dragon has no humans on board and is set to return into the earth’s atmosphere later this afternoon at around 1.30pm GMT.
Express.co.uk has approached SpaceX for comment.