WASHINGTON, D.C. — President Donald Trump said Tuesday that he had fired national security adviser John Bolton, announcing in a tweet that he’d told him Monday night that “his services are no longer needed” after the two had repeatedly clashed over foreign policy priorities and decisions.

The abrupt ouster of Trump’s third national security adviser comes as the White House grapples with a series of fraught challenges, including Trump’s cancellation of peace talks with the Taliban in Afghanistan, his trade war with China, his “maximum pressure” campaign against Iran, and his yet-unsuccessful attempts to convince North Korea to give up its nuclear arsenal.

While Trump said he would name a new national security adviser next week, the latest high-level shake-up at the White House raised fresh doubts about Trump’s stewardship of foreign policy — and control of his own staff — as he heads into his reelection campaign.

As often happens under Trump, there was immediate confusion as to the sequence of events, and under what circumstances, with Trump and Bolton offering conflicting accounts of whether Bolton had resigned or been fired.

Trump tweeted around noon Monday that he had informed Bolton of his decision “last night,” adding, “I disagreed strongly with many of his suggestions, as did others in the Administration.”

“I asked John for his resignation, which was given to me this morning. I thank John very much for his service,” he said.

But Bolton contradicted that sequence of events, throwing into question whether the two men had a face-to-face discussion about the firing, something Trump has avoided in making other major personnel changes.

“I offered to resign last night and President Trump said, ‘Let’s talk about it tomorrow,’” Bolton tweeted about 10 minutes after Trump’s announcement.

As is typical under Trump, the firing unfolded on Twitter and Fox News in dramatic fashion. Bolton, from the White House, texted Fox News host Brian Kilmeade while he was on the air.

“John Bolton just texted me, just now, he’s watching,” Kilmeade said on the air. “He said, ‘Let’s be clear, I resigned.’”

Less than an hour earlier, the White House had notified reporters that Bolton would appear at a 1:30 p.m. briefing with two Cabinet officials.

Trump’s announcement came as a shock, even though Bolton’s increasing isolation from Trump and lack of influence on foreign policy matters were no secret within the White House.

Bolton, a prominent hawk whom the president liked from his many appearances on Fox News, was appointed in April 2018 and lasted almost a year and a half in the job, advocating aggressive stances toward Iran, North Korea and Afghanistan.

Bolton also took the lead on Venezuela, assuring Trump that socialist President Nicolas Maduro could be easily ousted from office. At one press briefing, Bolton stood with a notepad visible to the cameras on which he’d scrawled a line about “5,000 troops to Venezuela” that appeared to be a threat of a U.S. incursion.

Trump invested political capital in the project, welcoming Venezuelan opposition figures into the Oval Office and declaring recognition of opposition leader Juan Guaido as the legitimate president of the beleaguered country. But nine months later, Maduro has not budged, the opposition is flailing and the entire mission has stalled.

Although Trump appreciated Bolton’s tough talk, the two often clashed when formulating policy. Trump ran for president on a platform of reducing involvement in foreign conflicts, and he viewed Bolton as too eager to advocate military force.

When Trump made his dramatic crossing into the Korean demilitarized zone in June, grasping hands with North Korean dictator Kim Jong Un, Bolton had been dispatched to Mongolia. Secretary of State Michael R. Pompeo, the president’s daughter Ivanka and son-in-law Jared Kushner were present, but the national security adviser was more than a thousand miles away.

Tensions between Bolton and other top members of Trump’s national security team, including Pompeo, have worsened, as Bolton pushed back on several of the president’s initiatives.

After Trump canceled his proposed meeting last weekend at Camp David with members of the Taliban and the Afghan government, stories quickly emerged that Bolton had strongly opposed the summit and the proposed peace deal with the Taliban.