The role of Elon Musk's SpaceX in an ambitious new U.S. missile defense system is in question following the dramatic feud last week between the billionaire entrepreneur and President Donald Trump, according to three people familiar with the project.

On June 5, as the feud between the two erstwhile besties escalated, Trump posted on his Truth Social Platform, “The easiest way to save money in our Budget, Billions and Billions of Dollars, is to terminate Elon’s Governmental Subsidies and Contracts. I was always surprised that Biden didn’t do it!”