SpaceX launched a crewed NASA mission on Friday to return two astronauts from the International Space Station, after technical issues with Boeing’s spacecraft extended their stay for nine months, leading SpaceX CEO Elon Musk and President Donald Trump to suggest they were stranded for “political reasons.”

NASA astronauts Butch Wilmore and Suni Williams arrived at the ISS aboard Boeing's Starliner spacecraft last June. The duo were flying the capsule's first crewed flight test, which was expected to stay in orbit for about 10 days before flying the pair back to Earth.