Two of President Donald Trump's top officials intended to unveil new steps to strengthen counterterrorism sanctions Tuesday — but spent the bulk of their time fending off questions about the messy exit of former national security advisor John Bolton, which Trump had announced about an hour earlier.

Bolton was scheduled to appear alongside Secretary of State Mike Pompeo and Treasury Secretary Steven Mnuchin at the White House for a press briefing, the details of which were not immediately clear.

But about an hour before the briefing was set to begin, Trump tweeted that he "informed" Bolton on Monday night "that his services are no longer needed at the White House."

"I asked John for his resignation, which was given to me this morning," Trump wrote.

Bolton challenged Trump's claim minutes later, tweeting, "I offered to resign last night and President Trump said, 'Let's talk about it tomorrow.'" In a text to NBC News, he added: "I offered to resign last night. He never asked for it, directly or indirectly. I slept on it, and resigned this morning."

The sudden news of Bolton's departure took center stage in the question-and-answer portion of the briefing, which lasted roughly 15 minutes.

Asked if the Cabinet officials were "blindsided" by the shake-up, a smirking Pompeo responded: "I'm never surprised."

At the top of the briefing, Pompeo and Mnuchin had revealed a new executive order giving the Treasury and State departments new tools to better target and label terrorists around the world. The new order has already been used to slap sanctions on multiple individuals and entities, Mnuchin said.

"The government has taken more action than we ever have before," Mnuchin said.

"Today's executive order marks the most significant update to counterterrorism sanctions authorities since September of 2001," Pompeo said.

This is developing news. Please check back for updates.