(Reuters) -Elon Musk's rocket company SpaceX will begin decommissioning its Dragon spacecraft immediately, the billionaire said on Thursday in response to U.S. President Donald Trump's statement that the government should cancel Musk's federal contracts.

NASA relies on SpaceX's Dragon spacecraft to ferry astronauts to and from the International Space Station under a contract worth roughly $4.9 billion. The capsule is the only U.S. spacecraft capable of flying humans in orbit.

Musk's statement marks a dramatic escalation in an intensifying fight with Trump that burst into public view this week, when Musk opposed the Trump administration's linchpin spending bill.

Taking Dragon out of service would disrupt the ISS program, which involves dozens of countries under an international agreement signed over two decades ago. Russia's Soyuz system is the only other crewed spacecraft that sends astronauts to the ISS.