'If what I tell you becomes public, POTUS will be impeached': What Lt. Col. Alexander Vindman told brother after hearing Trump 'crossing brightest of bright lines' by asking Ukraine leader to investigate Bidens, his memoir reveals

Retired Lt. Col. Alexander Vindman revealed on Sunday that he went 'straight upstairs' to his twin brother's White House office after Donald Trump crossed 'the brightest of bright lines' in his infamous call with Ukrainian President Volodymyr Zelensky where he asked for an investigation into Joe and Hunter Biden.

'I go straight upstairs into the legal suite, and my twin brother's office is almost as soon as you walk in. I go in, close the door and I tell him "Eugene, If what I'm about to tell you becomes public, the President will be impeached,"' Vindman told CBS Sunday Morning.

Yevgeny Vindman was serving as chief ethics officer on the White House National Security Council when his brother led the Eastern Europe, Caucasus and Russia office of the NSC. 

Alexander Vindman told CBS Sunday Morning he was the 'driving force' behind Trump's impeachment

He sat down for an interview with his twin brother Yevgeny Vindman and father Semyon . All three had immigrated from Ukraine along with their older brother when the twins were children

Following Trump's request that Zelensky 'look into' the Bidens Vindman said he immediately told his twin brother Yevgeny, who was an ethics lawyer for the National Security Council (pictured: Military veterans Alexander and Yevgeny Vindman at the Pentagon in 2016)

He told CBS the pair's minds were 'quickly made up about what actions we would take and what our duty was' after a conversation that lasted five minutes.

Vindman also said he was the 'driving force' behind Donald Trump's first impeachment proceedings in an interview ahead of the Tuesday release of his memoir, Here, Right Matters.

Vindman made his bombshell statements on a media tour promoting his memoir Here, Right Matters, which goes on sale August 3

'I was the driving force behind this whole thing,' the former national security official and star hearing witness said. 'I'm getting some chills thinking about it right now.'

However he maintained he 'had no thoughts about this ever becoming public.'

In a Sunday op-ed Vindman revealed he sensed something was wrong when Trump's phone call with Zelensky, which was expected to be a routine call to congratulate a fellow head of state on the previous day's parliamentary election, 'was abruptly rescheduled for the morning of July 25 with no explanation.'

It came weeks after Trump placed an 'unexplained' hold on military aid to Ukraine amid the country's ever-going threat from Russia.

'The national-security apparatus had gotten used to the president's inattention to any policy, let alone foreign policy, so this sudden White House interest in Ukraine was something new, and deeply unsettling,' Vindman wrote in The Atlantic. 

He recalled Trump had a 'detached, unfriendly' tone through most of the call even as Zelensky attempted to build a rapport with the then-president. 

After asking the comedian-turned-Ukrainian leader to investigate a 'bizarre conspiracy' that Ukrainian actors were involved in Robert Mueller's investigation and behind the 2016 DNC hack, Vindman said Trump broached the topic of Hunter Biden.

Vindman accused Trump of crossing the 'brightest of bright lines' when he realized the president was reportedly holding up military aid to Ukraine in exchange for Zelensky opening an investigation into Trump's then-presidential opponent Joe Biden

Vindman said the call grew worse when Trump asked Zelensky to work with then-Attorney General Barr to investigate Joe and Hunter Biden over allegations the former VP stopped an investigation into his son's dealings with a Ukrainian energy company

'My head snapped up. I looked quickly around the table. Were others tracking this?' Vindman wrote. 

Trump claimed Joe Biden was responsible for stopping an investigation into Hunter Biden's activities on the board of Ukraine energy company Burisma - which Vindman called baseless. 

'Even if there had been anything to this Biden story, the president’s bringing up such an allegation against a political rival, or any American citizen at all, and demanding an investigation on a call with a foreign head of state was crossing the brightest of bright lines,' the retired Army officer claimed. 

Alexander Vindman arrives to testify during the House Select Intelligence Committee hearing on the impeachment inquiry into President Donald Trump on November 19 2019

He said Trump's request that Zelensky look into his then-opponent and his adult son amounted to 'extorting Ukraine to damage a political challenger at home and boost his own political fortunes.'

He added that he had 'no choice but to report' Trump's 'misconduct.' 

His brother Yevgeny was the first person he went to because he was 'uniquely positioned' to advise him, Vindman claimed.

'He would protect, at all costs, my telling the truth.'

Yevgeny Vindman compared the days between his brother's bombshell testimony and when both twins were let go from the White House to 'being in the middle of an enemy camp.'

'I was surprised that it took 'til Friday before we were both marched out,' he said.