Since coming to office in January 2017, US President Donald Trump's administration has witnessed the departure - at times forced - of a number of high-ranking officials.

Among the most high-profile firings and resignations are EPA director Scott Pruitt, Secretary of State Rex Tillerson and FBI Director James Comey.

Al Jazeera takes a look at some of the Trump administration departures.

Jeff Sessions - Resigned

US Attorney General - Resigned November 2018

Sessions announced his resignation just a day after the Democrats gained control of the House of Representative in the 2018 US midterms.

Trump's criticism of Sessions stemmed over Sessions decision to recuse himself from an investigation into Russian meddling in the 2016 US presidential election.

The US president blamed the decision for opening the door to the appointment of special counsel Robert Mueller, who took over the Russia investigation and began examining whether Trump's hectoring or Sessions was part of a broader effort to obstruct justice and stymie the probe.

Nikki Haley - Resigned

US ambassador to the United Nations - Resigned October 2018

Haley was appointed to the UN post in November 2016. Before she was named by Trump to her UN post, Haley was governor of South Carolina, the first woman to hold the post. She was re-elected in 2014.

Haley was an unusual pick for UN envoy. As South Carolina governor, she was outspoken in her criticism of Trump during the 2016 campaign - a stance that effectively disqualified other candidates for top administration positions.

The daughter of Indian immigrants, Haley alluded to Trump in denouncing "the siren call of the angriest voices" who disrespected America's immigrants. Trump tweeted that "The people of South Carolina are embarrassed by Nikki Haley".

Scott Pruitt- Resigned

Administrator of the Environmental Protection Agency - Resigned July 2018

Trump accepted Pruitt's resignation following an intractable scandal that had engulfed the Environmental Protection Agency (EPA) under his tenure.

Pruitt, a known climate-denier and the man helming the EPA's systematic roll-back of Obama-era environmental regulations, had faced relentless media scrutiny after it was revealed he rented accommodation linked to a sympathetic energy lobbyist.

"Within the Agency Scott has done an outstanding job, and I will always be thankful to him for this," Trump said in a tweet, following Pruitt's resignation.

Pruitt's deputy, former coal lobbyist and climate denier Andrew Wheeler, will take over as Acting Administrator of the EPA.

Lt General HR McMaster - Resigned

National Security Adviser - Resigned March 2018

A White House source told Al Jazeera that Trump and McMaster "mutually agreed" on the decision for the national security adviser to resign.

The source denied that the reshuffle was related to recent developments in Trump's cabinet, saying it was the result of "ongoing conversations" between the two officials.

In confirming his resignation, McMaster also announced his retirement from the US Army.

Trump announced on Twitter that McMaster will be replaced by former US Ambassador to the UN John Bolton.

Andrew McCabe - Fired

Deputy FBI Director - Fired March 2018





After his firing in March as the FBI deputy director, Andrew McCabe said he had been targeted because he is a crucial witness into whether President Donald Trump tried to obstruct the Russia investigation.

According to the Justice Department, McCabe had leaked information to reporters and misled investigators about his actions - allegations he denied.

"Here is the reality: I am being singled out and treated this way because of the role I played and the actions I took, and the events I witnessed in the aftermath of the firing of James Comey," McCabe said in a lengthy statement following his firing.

McCabe corroborated former FBI Director James Comey's claims that Trump tried to pressure him into ending the Russia probe.

Rex Tillerson - Fired

Secretary of State - Fired March 2018

Tillerson, a former top executive of the energy giant Exxon, took office on February 1, 2017. His relationship with Trump quickly turned rocky over the Iran nuclear agreement, the Gulf crisis, and North Korea's nuclear weapons.

But things took a serious turn for the worse in October after news reports broke that Tillerson described the US president as a "f$@&ing moron".

Tillerson denied he had insulted his boss, but their relationship apparently couldn't recover.

Steve Bannon - Resigned

Chief Strategist - Resigned August 2017



Bannon co-founded Breitbart News, a website with the purported goal of countering mainstream media and providing a platform for movements at the right-end of the political spectrum.

The 64-year-old's relationship with the president soured following speculation he was leaking compromising information to the press, and complaining about not receiving enough credit for his policy contributions.

He presented his resignation on August 4, 2017.

Michael Flynn - Resigned

National Security Adviser - Resigned February 2017



Flynn, a former army general, joined Trump early on the campaign trail and assumed the national security adviser role in January 2017 - only to resign less than a month later amid an ongoing investigation into alleged Russian meddling in the 2016 elections.

He has since pleaded guilty to lying to the FBI in that investigation.

James Comey - Fired

FBI Director - Fired May 2017

Former FBI director James Comey was fired by Trump in May 2017.

Comey was leading an ongoing investigation into alleged Russian interference in the 2016 presidential election.

His dismissal raised fears the president was looking to disrupt the integrity of the inquiry.

Reince Priebus - Resigned

White House Chief of Staff - Resigned July 2017



By the time he resigned, Reince Priebus had become the shortest serving chief of staff in US history.

Unable to contain the chaos that came to characterise the Trump administration's early days, he was reportedly forced out and replaced by current chief of staff - and former homeland security secretary - retired general John Kelly.

He resigned on June 28, 2017.

Sally Yates - Fired

Acting Attorney General - Fired January 2017

Yates, who was appointed by former President Barack Obama as acting attorney general, lasted a total of 10 days in the Trump presidency.

As the country's top law enforcement official, Yates instructed justice department lawyers not to defend the president's ban on people from seven Muslim-majority countries.

She was fired on January 30, 2017.

Anthony Scaramucci - Fired

White House Communications Director - Fired July 2017

A declared opponent of former chief of staff Reince Priebus, Scaramucci arrived at a time of tumult characterised by media leaks and speculation of disunity among White House personnel.

His appointment prompted the voluntary departure of former press secretary Sean Spicer and Priebus less than a week later.

Scaramucci, nicknamed "The Mooch", was asked to step down in July 2017 - less than two weeks of taking the job - after he gave an expletive-filled interview to The New Yorker denouncing Priebus and Bannon. He defended himself by saying he sometimes used "colourful language".

Sean Spicer - Resigned

White House Press Secretary - Resigned July 2017



Sean Spicer resigned from the press secretary post on July 21, 2017, after making it known to Trump that he vehemently disagreed with his choice of Scaramucci as White House communications director.

The 46-year-old became the subject of media scrutiny for remarks such as saying Adolf Hitler had humanity for not resorting to chemical weapons, in a speech meant to highlight the Syrian government's cruelty.

Gary Cohn - Resigned

Chief Economic Adviser - Resigned March 2018

Trump's top economic adviser and chief of the National Economic Council, Cohn was apparently disillusioned with the recent tariffs that the president was contemplating - and has since signed into law.

Cohn resigned in protest on March 6.

Preet Bharara - Fired

US Attorney for the Southern District of New York - Fired March 2017

Bharara, former US attorney for the Southern District of Manhattan, was fired in March 2017, after he refused to abide by Attorney General Jeff Sessions' request - at Trump's behest - that all 46 US attorneys appointed by Obama step down.

Rob Porter - Resigned

White House Staff Secretary - Resigned February 2018

Rob Porter resigned in February 2018 after reports that the staff secretary physically and emotionally abused two ex-wives.

Porter denied the allegations but said in a statement he could no longer "engage [the] public with a coordinated smear campaign".

Hope Hicks - Resigned

White House Communications Director - Resigned February 2018

Hope Hicks was one of the first to join Trump on the campaign trail.

Her resignation came on February 28, a day after giving testimony before the House Intelligence Committee, where she admitted to telling "white lies" in defence of President Trump.

Hicks was Trump's fifth communications director in a little over a year.

Tom Price - Resigned

US Secretary of Health and Human Services - Resigned September 2017



Known as a frugal congressman who railed against abuse of power and misuse of state funds, Price was caught in a media firestorm when it was discovered he cost taxpayers an estimated $1m for his use of private planes during short trips.

He announced his resignation on September 29, 2017.

Sebastian Gorka - Resigned

Deputy Assistant to the President - Resigned August 2017

A former Breitbart staffer and close confident of chief strategist Steve Bannon, Gorka signalled his departure on August 25, 2017.

It is widely believed that Bannon's resignation a week earlier determined his decision.

Others who have resigned or been fired:

Thomas Homan, Acting Immigration and Customs Enforcement Director, Resigned June 2018

Tom Bossert, Homeland Security Advisor, Resigned April 2018

David Shulkin, Secretary of Veteran's Affairs, Fired March 2018

Rick Dearborn, Chief of Staff for Legislative and Intergovernmental affairs, Resigned December 2017

Brenda Fitzgerald, Centre for Disease Control and Prevention Director, Resigned January 2018

Omarosa Manigault, Director of Communications for White House Office of Public Liaison, Resigned January 2018

Tom Price, Secretary of Health and Human Services, Resigned September 2017

Michael Dubke, Communications Director, Resigned May 2017

Walter Shaub, Office of Government Ethics Director, Resigned July 2017

Katie Walsh, Deputy White House Chief of Staff, Resigned March 2017

**According to US media there are at least a dozen others who have been fired or left the White House since Trump took office.