U.S. President Donald Trump’s National Security Advisor, John Bolton, stepped down on Tuesday, nearly a year-and-a-half after he took the post in April 2018.

Whether he was fired or resigned depends on whom you ask. While President Trump says he ousted Bolton, the former national security advisor argues that he left his post on his own accord.

Bolton’s departure came amid a growing split between Trump and the hawkish aide on various foreign policy issues. Trump’s decision to negotiate with the Taliban at Camp David just days before the 18th anniversary of the 9/11 attacks closely preceded his exit.

Echoing members of his administration, Trump said Bolton’s policy views were no longer in line with his own.

“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 wrote on Twitter Tuesday:

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

Bolton took office as national security advisor on April 9, 2018.

Below are five policy initiatives pushed by Bolton during his tenure:

Afghanistan

The Wall Street Journal (WSJ) notes that Bolton was opposed to Trump negotiating with the Taliban face-to-face on U.S. soil days before the anniversary of the 9/11 attacks Wednesday.

U.S. troops invaded Afghanistan soon after the September 11 massacre, in October 2001, to remove the Taliban regime for harboring the attack’s perpetrator al-Qaeda. On Saturday, the president announced that he had canceled a secret Camp David meeting with the Taliban, citing a recent attack by the terrorist group that killed an American.

WSJ reported:

Mr. Bolton has disagreed with the president on several foreign policy issues—including, most recently, the president’s interest in meeting with Taliban leaders at Camp David to negotiate a possible peace deal in Afghanistan. … Mr. Bolton’s offer to resign came during a contentious conversation with Mr. Trump about Afghanistan on Monday before the president left for a campaign rally in North Carolina, according to a person familiar with the conversation. Mr. Trump grew frustrated that Mr. Bolton continued to oppose the president’s plan to strike a peace deal with the Taliban and the Afghan government. Mr. Bolton has supported drawing down troops in Afghanistan.

Sen. Lindsey Graham (R-SC) also indicated that Bolton abandoned ship over the controversy surrounding the meeting between the president and the Taliban at Camp David. The Senator is a Trump ally and Bolton supporter.

“I knew there were some concerns about the Taliban meeting, but I didn’t know for sure,” Graham told WSJ. “He gave the president his honest opinion, and it’s time for him to move on.”

Trump did cancel the meeting with the Taliban on Saturday, a day before it was scheduled to take place.

Iran

Considered a crucial policy victory for the anti-Tehran hawk, Bolton oversaw Trump’s withdrawal from the controversial 2015 nuclear deal between the United States and U.S.-designated state-sponsor of terror Iran.

Trump reimposed sanctions suspended under the accord as part of an unprecedented wave of restrictions that are crippling the Iranian economy, hindering Tehran’s ability to fund terrorist groups.

Bolton also advised Trump to designate Iran’s Islamic Revolutionary Guards Corp (IRGC) a foreign terrorist organization in April. The move resulted in the imposition of wide-ranging economic and travel sanctions on the group, companies, and individuals associated with it. The IRGC is a formal arm of the Iranian state military; the designation was unprecedented.

Citing an unnamed Trump administration, official, the New York Times noted that Bolton “pushed” for the designation.

United Nations

Bolton also oversaw the scaling back of U.S. financial contributions for the United Nations.

The adviser helped Trump keep his promise of reducing American’s foreign financial commitments.

Foreign Policy reported in October 2018:

In early July, a U.S. State Department political appointee fired off an email to the National Security Council detailing how to thwart Congress’s intent to fund a range of United Nations international aid programs opposed by White House conservatives, including initiatives benefiting Palestinian refugees and providing reproductive health services to impoverished women.

Venezuela

The Trump administration recognized Juan Guaidó as the interim president of Venezuela and declared socialist dictator Nicolás Maduro as illegitimate during Bolton’s tenure.

An unnamed former Trump administration official indicated to NBC News that Bolton “worked closely with [Vice-President Mike] Pence on multiple issues, including efforts to replace Venezuelan leader Nicolas Maduro.”

Bolton successfully lobbied on behalf of tough sanctions on the Maduro regime.

The former national security adviser also signaled support for U.S. military intervention against Maduro in Venezuela.

Despite the maximum pressure policy on the Maduro regime, the Trump administration has failed to remove the dictator.

China and North Korea

Bolton encouraged a hardline stance on China, the former Trump administration official told NBC News. Trump declared a trade war against China while Bolton was in office.

In April 2018, the South China Morning Post (SCMP) pointed out:

Trump’s appointment of John Bolton as national security adviser and his nomination of Mike Pompeo, the former CIA director, as secretary of state seem to herald a more hardline and rightward shift in Trump’s foreign and security policies. … The duo [is] not only widely seen as conservative firebrands and hardliners, [but] they are also known for their China-bashing. … A trade war has been steadily building, not to mention growing tensions over Taiwan and escalating disputes on the South China and East China seas.

Last month, the former adviser also urged the U.K., an American ally, to step up pressure against Beijing in line with the Trump administration’s position.

Referring to Bolton’s trip to London last month, Reuters noted:

Trump has also pushed Britain to get tougher on China’s Huawei out of concern its next-generation 5G technology represents a national security risk. Washington wants its allies, including Britain, to avoid using equipment from Huawei. … Bolton plans to argue that Huawei is an arm of the Chinese government and that its hardware could be used to monitor communications that go through its system.

The fundamental differences between the views of Trump and Bolton were at full display during the denuclearization negotiations with North Korean dictator Kim Jong-un. It appears that the president and his adviser were playing good cop and bad cop, respectively. Bolton has advocated for a tougher stance, including military intervention, in North Korea.

“Take North Korea, for starters. Trump relished showy summits with Kim Jong-un, the country’s ruthless leader,” USA Today noted. “Bolton was skeptical that such talks would amount to anything.”

The former national security adviser also expressed doubts that Kim would give up his nuclear efforts.

Reuters noted, “Policy analysts say Bolton’s departure could help U.S. efforts to revive the talks but will not make Washington’s aim of persuading Pyongyang to give up its nuclear weapons any easier.”

Bolton served under Republican Presidents George W. Bush, Ronald Reagan, and George H.W. Bush. He is a respected and influential force in conservative political circles.