US Veterans Affairs Secretary David Shulkin has fired a parting shot at the White House a day after being fired by President Donald Trump.
Mr Shulkin said figures within the administration were planning to privatise veterans' healthcare, and he lost his job because he opposed them.
President Trump replaced Mr Shulkin on Wednesday with the White House doctor, Rear Admiral Ronny Jackson.
It was the latest in a series of departures from Mr Trump's cabinet.
This month alone, the president has fired Secretary of State Rex Tillerson and National Security Adviser HR McMaster, while his top economic adviser Gary Cohn also left. Meanwhile, White House communications director Hope Hicks' last day was on Thursday.
Mr Trump announced Mr Shulkin's sacking on Twitter, posting: "I am thankful for Dr David Shulkin's service to our country and to our GREAT VETERANS!"
What did Shulkin say?
In a scathing column for the New York Times, Mr Shulkin wrote: "As I prepare to leave government, I am struck by a recurring thought: It should not be this hard to serve your country."
He said that in recent months "the environment in Washington has turned so toxic, chaotic, disrespectful and subversive that it became impossible for me to accomplish the important work that our veterans need and deserve".
The former hospital administrator, who first served under President Barack Obama, said that "advocates within the administration for privatising" veterans' healthcare services "saw me as an obstacle to privatisation who had to be removed".
It is traditional for departing cabinet secretaries to thank the president for granting them the opportunity to serve, but Mr Shulkin pointedly made no reference to Mr Trump.
Why was Shulkin under a cloud?
In an interview with National Public Radio (NPR) on Thursday morning, Mr Shulkin said a critical report by an internal watchdog had been used by the White House as a pretext to get rid of him.
The inspector general's report found that Mr Shulkin and his wife used an official trip to Europe last summer to sightsee and improperly accepted tickets for the Wimbledon tennis tournament.
"There was nothing improper about this trip, and I was not allowed to put up an official statement or to even respond to this by the White House," he said.
"I think this was really just being used in a political context to try to make sure that I wasn't as effective as a leader moving forward."
The internal watchdog determined the secretary and his wife had spent nearly half the nine-day business trip in "sightseeing and other unofficial activities".
Mr Shulkin agreed last month to reimburse the government for his wife's airfare, which was more than $4,300.
How will Ronny Jackson fare?
Some veterans organisations are questioning Rear Adm Jackson's qualifications.
The 50-year-old has worked as White House physician during the last three administrations, serving George W Bush and Barack Obama before Mr Trump moved into the White House.
He caught public attention a year ago after Mr Trump's medical, telling reporters the president was in "excellent health".
The rear admiral has a wealth of military experience, having served with a Marine unit during the war in Iraq.
But he comes into the veterans' post, which entails running a vast department, with little administrative or political experience.
Joe Chenelly, the national executive director of American Veterans, said: "We are disappointed and already quite concerned about this nominee.
"The administration needs to be ready to prove that he's qualified to run such a massive agency, a $200 billion bureaucracy," he added.
Veterans of Foreign Wars noted that the nominee's background "does not reflect any experience working with the VA or with veterans, or managing any organisation of size".