Elon Musk warns there's a growing risk of a US default as the deadline to raise the debt ceiling looms

• Elon Musk has warned that a US debt default appears "increasingly possible." 
• Government officials are scrambling to reach a deal to raise the debt ceiling.
• Treasury Secretary Janet Yellen has cautioned the US could run out of money as early as June 1.

There's a growing risk that the US government will default on its debt,  Elon Musk has warned.

A Twitter user, Whole Mars Catalog, wrote that "defaulting on the national debt is a bad idea" in a recent tweet. Musk — the CEO of Tesla, SpaceX, and Twitter — replied with two worrying words: "Increasingly possible."