The worried reaction within space and national security agencies highlights the risks of government’s exclusive dependence on SpaceX for crucial tasks, including classified missions.

President Donald Trump's threat to cancel Elon Musk's government contracts would have far-reaching implications, experts said.

The president could tighten federal oversight of the tech titan’s businesses, even if heavy reliance by the Pentagon and NASA on them makes terminating Mr. Musk’s contracts less feasible.