President Donald Trump has asked national security adviser John Bolton to resign, effective immediately. The announcement came in a tweet on Tuesday, less than two hours before a press briefing at the White House that Bolton was expected to attend.

The news may come as a surprise to some, but it’s not nearly as unexpected as it may seem. Trump is known for his trademark ‘Art of the Deal’ style. Although he talks tough and often follows through on certain threats, he isn’t a warhawk. Bolton, on the other hand, is famous for his hardline and somewhat trigger-happy approach to military conflicts. He was probably brought on board in a more symbolic role to create the perception of a sort of ‘good cop, bad cop’ dynamic.

That dynamic seems to have outlived its usefulness as disagreements between the two became too large to overcome.

“Simply put, many of Bolton’s policy priorities did not align with POTUS,” White House press secretary Stephanie Grisham said in a comment to Yahoo News.

It is known that Trump and Bolton strongly disagreed on how to approach relations with North Korea and Iran. Some sources speculate that Trump and Bolton may have recently clashed over how to handle the situation in Afghanistan.

Other unconfirmed sources allege the departure may also be due to suspicions that Bolton was involved in leaks.

Either way, it is believed that secretary of state Mike Pompeo was supportive of Trump’s decision.

Bolton, who has advised previous administrations, including Bush’s in the lead-up to the Iraq War, tweeted that he offered to resign the night before.