"After 21 years, six months and 10 days of active military service, I am now a civilian. I made the difficult decision to retire because a campaign of bullying, intimidation and retaliation by President Trump and his allies forever limited the progression of my military career," he wrote.
Mr Vindman experienced attacks from President Trump after he testified before Congress during the president's impeachment hearings. His testimony became key in the impeachment inquiry, as he expressed alarm over Mr Trump's phone call with Ukraine President Volodymyr Zelensky. During the phone call, Mr Trump asked for the country to open an investigation into political rival Joe Biden.
His op-ed went on to warn about the dangers of the Trump administration against those who speak out about the president.
“At no point in my career or life have I felt our nation’s values under greater threat and in more peril than at this moment. Our national government during the past few years has been more reminiscent of the authoritarian regime my family fled more than 40 years ago than the country I have devoted my life to serving,” he wrote.
The Iraq veteran and Purple Heart recipient was born in the Soviet Union but left at the age of three following the death of his mother.
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