US President Donald Trump has fired National Security Adviser John Bolton, saying he has “disagreed strongly with many of his suggestions.”

“I informed John Bolton last night that his services are no longer needed at the White House. I disagreed strongly with many of his suggestions, as did others in the Administration, and therefore I asked John for his resignation, which was given to me this morning,” Trump said in a tweet.

John Bolton resignation letter

“I thank John very much for his service. I will be naming a new National Security Adviser next week.”

This comes about 90 minutes before Bolton was expected to appear at a press briefing with Secretary of State Mike Pompeo and Treasury Secretary Steven Mnuchin.

Bolton offered a different version of events than Trump, saying: "I offered to resign last night and President Trump said, ‘Let's talk about it tomorrow.’”

....I asked John for his resignation, which was given to me this morning. I thank John very much for his service. I will be naming a new National Security Advisor next week.

— Donald J. Trump (@realDonaldTrump) September 10, 2019

Trump had sometimes joked about Bolton's image as a warmonger, reportedly saying in one Oval Office meeting that "John has never seen a war he doesn't like."

Bolton's departure comes as tensions with Iran are escalating in the Persian Gulf, North Korea continues to develop its weapons capabilities, arms control experts are warning of a potential nuclear arms race with Russia and trade tensions with China are intensifying, while Trump is discussing a drawdown of forces in Afghanistan.

After Trump's tweet Bolton said that live on Fox News, "'Let's be clear, I resigned.'"