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."

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