Musk attacked Trump directly over his signature spending bill for the first time Thursday, sparking an explosive back-and-forth.

An intense public feud erupted on Thursday between President Donald Trump and his one-time ally, billionaire Elon Musk, with an argument about Trump’s massive tax and domestic policy bill raging across social media and in the Oval Office.

Trump and Musk are engaging in public fights on social media. Here’s a timeline of the highs and lows of Musk and Trump’s bromance.