“Last night, I informed John Bolton that his services were no longer needed at the White House. I strongly disagree with many of his proposals, like others in the administration, and therefore I asked John to resign, ”Trump wrote on Twitter.

He thanked Bolton for his work, noting that he would give the name of the new National Security Advisor next week.

.... 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

In early August, Trump announced the resignation of US National Intelligence Deputy Director Sue Gordon.