Lt. Colonel Alexander Vindman wrote in The Washington Post op-ed on Saturday explaining that he stands by his decision to be a key witness in President Donald Trump‘s impeachment inquiry, despite sacrificing his career.

“When I was asked why I had the confidence to tell my father not to worry about my testimony, my response was, ‘Congressman, because this is America,” Vindman wrote.

“To this day, despite everything that has happened, I continue to believe that in America, right matters. I want to help ensure that right matters for all Americans,” he continued.

After Vindman testified on Trump’s call with Ukrainian President Volodymir Zelensky last year, he retired from the army after 21 years of service due to what he later called “campaign of bullying, intimidation, and retaliation” from Trump and his allies.

In his essay, Vindman also compared the leadership in the U.S. to the Soviet Union, which he and his family fled when he was a child.

“Our citizens are being subjected to the same kinds of attacks tyrants launch against their critics and political opponents,” he wrote. “There is another way.”

Vindman said that even though the House testimony cost him his career, he expressed hopes for a better future in America.