A feud between US President Donald Trump and billionaire Elon Musk unfolded online Thursday, with Musk threatening to shut down a key spacecraft that NASA depends on for transporting astronauts and cargo to the International Space Station (ISS).

The tension began after Trump suggested ending federal contracts with Musk’s companies—SpaceX and Starlink.

In response, Musk posted on X (formerly Twitter) that SpaceX would “begin decommissioning its Dragon spacecraft immediately.”

It’s unclear whether Musk intends to follow through. However, the Dragon capsule—developed with federal funding—plays a critical role in maintaining ISS operations.

NASA heavily relies on SpaceX not only for space station missions but also for science launches and future moon landings.

The Dragon Capsule’s Role

Currently, SpaceX is the only American company capable of flying astronauts to the ISS using its four-person Dragon capsules. Boeing’s competing Starliner capsule has faced setbacks, including a troubled 2023 mission that ended with NASA astronauts returning to Earth aboard a SpaceX capsule nine months later. The Starliner remains grounded as NASA considers another test—possibly without crew.

In addition to NASA missions, SpaceX also uses the Dragon for private flights. The next one, arranged by Houston-based Axiom Space, is scheduled for next week. SpaceX’s cargo version of the capsule is also routinely used to deliver supplies to the ISS.

NASA’s Alternative: Russia

Aside from SpaceX, Russia’s Soyuz spacecraft is the only other current option for transporting astronauts. Each Soyuz flight carries three crew members—typically two Russians and one NASA astronaut. In turn, each SpaceX flight carries one Russian under a reciprocal agreement, ensuring that both nations always have crew aboard for emergency returns.

When SpaceX launched its first crewed mission for NASA in 2020, it allowed the U.S. to reduce dependence on Russia, which had been charging tens of millions of dollars per seat.

SpaceX’s Other NASA Ties

Beyond crewed flights, SpaceX has launched numerous NASA science missions and military payloads. The company also secured a contract to help safely deorbit the ISS when its mission ends.

Moreover, NASA has chosen SpaceX’s massive Starship rocket to land astronauts on the moon—at least for the first two missions. Although the rocket’s latest test flight ended in failure when it lost control and disintegrated, it remains central to NASA’s lunar plans.