US President Donald Trump announced in a tweet on Tuesday that he has asked national security adviser John Bolton to resign.
He noted that he "strongly disagreed with many" of Bolton's suggestions "as did others in the administration", and added that he would appoint a replacement next week.
The tweet came just an hour after the White House press office said Bolton was scheduled to appear at a press briefing alongside Secretary of State Mike Pompeo and Treasury Secretary Steve Mnuchin.
In his own Twitter message, Bolton disputed the president's account of his departure. "I offered to resign last night and President Trump said, 'Let’s talk about it tomorrow'," he tweeted.
According to reports, the two men disagreed on policies towards Afghanistan, North Korea and Russia.

Tanker crosses Strait of Hormuz as US waits for Iran's response to peace proposal
Twelve Pakistani police officers killed in car bombing and shootout
Qatar cargo ship targeted by drone, small fire with no injuries
Israeli strike kills seven in south Lebanon, health ministry says
Spanish health officials board hantavirus-hit ship to start evacuating passengers
