Washington CNN  — 

Former Veterans Affairs Secretary David Shulkin used an op-ed late Wednesday to blast “the environment in Washington” that “has turned so toxic, chaotic, disrespectful and subversive that it became impossible for me to accomplish the important work” of his job.

“As I prepare to leave government,” he wrote in an op-ed for The New York Times, “I am struck by a reoccurring thought: It should not be this hard to serve your country.”

In the piece, which came hours after President Donald Trump announced via Twitter that he would replace his VA secretary, Shulkin claimed he was “falsely accused of things by people who wanted me out of the way,” even though he wrote that he acted with “the utmost integrity.”

He listed what he said were accomplishments during his time as VA secretary. But, he claimed, “these successes within the department have intensified the ambitions of people who want to put VA health care in the hands of the private sector.”

“The private sector, already struggling to provide adequate access to care in many communities, is ill-prepared to handle the number and complexity of patients that would come from closing or downsizing V.A. hospitals and clinics, particularly when it involves the mental health needs of people scarred by the horrors of war,” Shulkin wrote, adding that the department’s understanding of veterans’ needs and its research “cannot be easily replicated in the private sector.”

Shulkin, the second member of Trump’s Cabinet to be ousted this month, did not address the controversy over his travel practices. A damning report from the department’s inspector general found “serious derelictions” by Shulkin and senior VA officials on a Europe trip last year. The report concluded that Shulkin had spent a good deal of the trip sightseeing and had inappropriately accepted a gift of Wimbledon tickets.

Shulkin’s earlier public comments on the matter rubbed White House officials, including chief of staff John Kelly, the wrong way. That frustration reached the White House recently, with Trump reportedly floating the idea in private of replacing Shulkin with Energy Secretary Rick Perry.

During his tenure in the Trump administration, Shulkin also grew increasingly isolated and at odds with top aides, including those in charge of VA communications efforts. The estrangement became so wide that the secretary had recently been conducting his own crisis communications effort via his personal cell phone, telling reporters that there were political staffers working to oust him.

“I came to government with an understanding that Washington can be ugly, but I assumed I could avoid all the ugliness by staying true to my values,” he wrote in the op-ed.

“Despite these politically-based attacks on me and my family’s character, I am proud of my record and know that I acted with the utmost integrity. Unfortunately, none of that mattered,” he added.

CNN’s Juana Summers and Jeremy Diamond contributed to this report.