John Bolton, the third U.S. national security advisor during the Trump administration, ended his tenure Tuesday, as his relationship with the president frayed over policy differences.

Bolton's exit has rid the Trump administration of one of its most hawkish figures, who actively pushed for tougher stance in dealing with Iran, the Taliban and others.

While Bolton's departure has dampened the mood of few inside Washington and around the world, and is expected to improve the flexibility of U.S. foreign policy, it's far from certain that the White House would embrace a softer tone.

NOT ALIGNED

U.S. President Donald Trump announced Tuesday Bolton's departure in a series of tweets, which was unexpected for many as the White House had put out a guidance earlier that had Bolton participating in a press briefing in the afternoon.

"I disagreed strongly with many of his suggestions, as did others in the administration, and therefore I asked John for his resignation," Trump tweeted.

Trump added that he had asked for the resignation on Monday night, and received it Tuesday morning.

Bolton quickly offered a counter narrative, saying he had offered his resignation Monday night. He later told a Fox News reporter: "Let's be clear, I resigned."

According to top officials of the Trump administration, Bolton, who entered office in April 2018, has had long-running policy differences with Trump.

Bolton's "priorities and policies just don't line up with the president," according to White House Spokesman Hogan Gidley.

It's no secret in Washington that Bolton and Trump had different ideas regarding a slew of foreign policy issues, including Iran, Venezuela, and the Democratic People's Republic of Korea (DPRK).

Bolton had been actively pushing for a military approach to Iran and Venezuela, and had called for exerting more pressure on the DPRK. The hard-line rhetoric was viewed to undermine Trump's campaign pledge to reduce U.S. overseas military operations, and ran counter to Trump's diplomatic efforts with the leaders of the DPRK and Iran.

U.S. media reported that the most recent fallout between Trump and Bolton erupted over a secret plan to invite Taliban leaders and the Afghanistan president to Camp David to hammer out a peace deal, which would help pave the way for a withdrawal from the war-torn country. Bolton reportedly opposed reaching a deal with the Taliban, triggering a heated argument between the two that led to the ousting.

NOT SURPRISING

While the announcement of Bolton's exit came at an unexpected timing, his departure has long been anticipated.

In an opinion piece published Tuesday, CNN said "it is surprising that Bolton's tenure even lasted this long," given his many clashes with Trump.

U.S. media had previously reported that Trump had been growing more impatient with Bolton as he became less convinced that Bolton's advice would hand him a major foreign policy victory during his first tenure in office.

The impatience have led to a public show of contradiction during Trump's visit to Japan earlier this year, when he denied he was seeking regime change in Iran, while Bolton asserted otherwise.

Republican senators had mixed response to Bolton's departure. Mitt Romney of Utah said it was "an extraordinary loss for our nation and for the White House," while Rand Paul of Kentucky said "the threat of war worldwide goes down exponentially" with Bolton's exit.

NEXT STEP

Trump said a fourth national security advisor will be announced next week, with Deputy National Security Advisor Charles Kupperman serving as an acting role in the interim.

U.S. media has put together a list of possible candidates who are likely to be tapped for the job, including Kupperman, U.S. envoy to the DPRK Stephen Biegun and U.S. envoy to Iran Brian Hook. Douglas Macgregor, a Fox News commentator, and U.S. ambassador to Germany Richard Grenell are also being floated as lesser possible picks.

With media reports that Trump had made at least one phone call to former national security advisor H.R. McMaster to make amends while Bolton was in office, some are speculating that the former general also have a slim chance at the job.

None of the candidates are known to pursue foreign policy as tough as Bolton's, raising hope that the White House would place more emphasis on diplomacy as it tackles global issues.

But in a press briefing Tuesday afternoon, U.S. Secretary of State Mike Pompeo warned against taking Bolton's departure as a sign of seismic shift in U.S. foreign policy.

"I don't think that any leader around the world should make any assumption that because some one of us departs that President Trump's foreign policy will change in a material way," he said.