After a rocky year and a half in the Trump administration, John Bolton is out as national security adviser. Just before noon on Tuesday, Donald Trump brusquely announced on Twitter that he had asked Bolton for his resignation. “I informed John Bolton last night that his services are no longer needed at the White House,” the president declared, prompting Bolton to text his own counter-narrative to Fox News. “Let’s be clear,” he wrote host Brian Kilmeade. “I resigned.”

The announcement appeared abrupt—Bolton had been scheduled to hold a media briefing with Secretary of State Mike Pompeo and Treasury Secretary Steve Mnuchin—but was hardly shocking to government insiders. Bolton—a notorious hawk—was always viewed as something of an odd fit for a national security adviser for a president who ran on a non-interventionist platform. “No one should be surprised at his departure,” a former top U.S. official who worked with Bolton in the Bush administration, told me. “Bolton was always a neocon cold warrior who was clearly adjusting every moment to try to push policies in a way that somehow overlapped with Trump’s priorities—usually domestic.”

There have long been reported tensions between Bolton and Pompeo—a not-so-unusual dynamic for a national security adviser and secretary of state, as I have previously reported. But according to CNN, the animus between the two had crescendoed amid disagreements over a sequence of foreign policy issues, including Iran, North Korea, China, and Venezuela. Those tensions spilled into Bolton’s relationship with the president over potential negotiations with the Taliban and efforts to withdraw U.S. troops from Afghanistan. The New York Times reported that Bolton opposed Trump signing an agreement with the Taliban, which the president was preparing to finalize at Camp David before announcing this past weekend that the talks were off. (The president wrote on Twitter that he called off the planned talks after the Taliban admitted to a suicide car bomb attack in Kabul “in order to build false leverage.”)

“In general, Ambassador Bolton just doesn’t represent the views of the president, and I think he was actively undermining the president in many ways on foreign policy and national security issues. If you look at, I think, the top four priorities of the last year for this administration, it’s been North Korea, Venezuela, Iran and now, Afghanistan. And in all four of those policy areas, Ambassador Bolton had a different view from that of the president,” Fernando Cutz, who served as a senior director on the NSC until last year, told me. “On North Korea, he was fundamentally opposed to engagement; on Venezuela, he kept threatening military action until the president yelled at him and told him to stop; on Iran, he was the one pushing for the strike that the president ended up pulling back from at the last minute and now, on Afghanistan, he was opposed to dialogue. So if you have someone as a top adviser and representative who disagrees with you on every issue you care about, it just doesn’t make sense.”

Bolton had been brought in to replace Trump’s second national security adviser, H.R. McMaster, with whom the president also frequently disagreed, in March 2018. But the two clashed early and often. “Trump has clearly shown that when he doesn’t like a national security adviser or their style isn’t his, he dismisses them,” a former senior State Department official, who also worked with Bolton, told me. “[It is] his right to do so. Every president gets to have the White House staff around them that best suits their style.”