WASHINGTON – President Donald Trump fired John Bolton as his national security adviser Tuesday, noting the two "disagreed strongly" on foreign policy matters.

Bolton's departure comes amid internal tension at the White House over negotiations with the Taliban to end the war in Afghanistan. Bolton, who was Trump's third national security adviser, opposed a planned secret meeting with the Taliban at Camp David that the president scuttled over the weekend.

"I informed John Bolton last night that his services are no longer needed at the White House," Trump wrote in a tweet. "I disagreed strongly with many of his suggestions, as did others in the Administration."

White House aides confirmed Bolton's disputes with administration officials in recent days, particularly over negotiations with the Taliban and the president's hopes for a withdrawal of U.S. troops from Afghanistan. Trump said he wants to reduce the number of service members in Afghanistan from about 14,000 to about 8,600, but some warned Trump not to strike a hasty deal to achieve that goal.

Bolton contradicted Trump's characterization of his departure, writing in a tweet minutes after the president's that he offered to resign.

"I offered to resign last night and President Trump said, 'Let's talk about it tomorrow,' " Bolton wrote.

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Bolton, a hawk on Iran, North Korea and a host of other global hot spots, was named to the post in March 2018, succeeding H.R. McMaster. Bolton's aggressive posture long appeared at odds with Trump's "America First" foreign policy, including his criticism of U.S. involvement in overseas conflicts.

In other ways, Bolton's pugnacious style – and his frequent appearances on Fox News questioning Russian interference in the 2016 presidential election – might have made him a natural fit in Trump's administration. Bolton served as President George W. Bush's ambassador to the United Nations and was an advocate for the invasion of Iraq in 2003.

Instead, aides said there was a general disagreement of temperament and style.

At an occasionally testy White House news conference, Secretary of State Mike Pompeo acknowledged disagreements with Bolton but said his departure would not change Trump’s foreign policy. Pompeo defended Trump’s decision to dismiss Bolton, who was originally expected to attend the briefing.

"I'm never surprised," Pompeo said with a grin when reporters asked if he was blindsided by the news. "And I don't mean that on just this issue."

Pompeo continued: "The president is entitled to the staff he wants."

Treasury Secretary Steven Mnuchin, appearing at the news conference with Pompeo, bristled when asked if Bolton’s departure means Trump’s national security team is a "mess."

“Absolutely not,” he said. “That’s the most ridiculous question I’ve ever heard.”

Bolton, a career diplomat, wanted to aggressively confront North Korea and Iran; Trump, a seat-of-the-pants novice, began to see Bolton as a warmonger. White House officials said it wasn't one thing that led to Trump's decision but an accumulation.

"Simply put, many of Bolton’s policy priorities did not align" with those of the president, said White House spokeswoman Stephanie Grisham.

"You can only say 'no, no, no' to a president so many times," said Aaron David Miller, a State Department negotiator for presidents of both parties who is a senior fellow at the Carnegie Endowment for International Peace. "North Korea, Iran, Venezuela and – last straw – Afghanistan."

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Before he joined the White House, Bolton had been a vocal advocate of regime change in Iran, a position Trump disavowed. Some lawmakers feared Bolton was pushing Trump into a perilous military confrontation with the Islamic Republic.

Bolton also took a hawkish stance on North Korea, pressing Trump to reject Kim Jong Un’s offer to partially dismantle his regime’s nuclear program and to instead demand a more sweeping denuclearization agreement. Trump has met three times with Kim and briefly stepped into North Korea at the Demilitarized Zone this year.

Before McMaster, the national security adviser job was held briefly by Michael Flynn, who pleaded guilty in 2017 to lying to FBI agents about his contact with Russian officials.

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Trump said he would name Bolton's replacement next week. White House spokesman Hogan Gidley said Charles Kupperman, Bolton's deputy, would fill the job in an acting capacity until Trump names a replacement.

Bolton's ouster drew mixed reaction on Capitol Hill. Sen. Rand Paul, R-Ky., applauded the move. Paul has long advocated for reduced U.S. military engagement abroad.

“I think the chances of war worldwide go greatly down," Paul said. "Bolton’s probably the leading advocate of the idea of regime change everywhere.”

Virginia Sen. Mark Warner, the top Democrat on the Senate Intelligence Committee, joked that "long-term job security in the Trump administration is, uh, not sure I would plan my career around it.”

Sen. Chris Murphy, D-Conn., a member of the Senate Foreign Relations Committee, said he was "shaken by the grave instability of American foreign policy."

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“I’m no Bolton fan, but the world is coming apart, and the revolving door of U.S. leadership is disappearing America from the world just at the moment where a stable American hand is most needed," Murphy posted on Twitter.

Sen. Mitt Romney, R-Utah, called Bolton a “brilliant man with decades of experience in foreign policy.” Bolton was an adviser to Romney's 2012 presidential campaign.

“His point of view was not always the same as everybody else in the room. That’s why you wanted him there," Romney said. "The fact that he was a contrarian from time to time was an asset, not a liability."

Contributing: Christal Hayes, Courtney Subramanian and Deirdre Shesgreen