If the allegations made by Washington Post journalists Bob Woodward and Robert Costa about Joint Chiefs of Staff Chairman Mark Milley assuring China they would be forewarned, should then-President Trump decide to launch a military attack, the top White House military advisor has violated the law and should be called before Congress to testify, according to retired Army Col. Douglas Macgregor.

Macgregor, who retired from the military in 2004 and became a senior Pentagon adviser to Trump-era Acting Secretary of Defense Christopher Miller, told "Tucker Carlson Tonight" he was not as surprised as much of the public by the allegation Milley essentially undermined his boss, the then-president, and gave comfort to a rival nation.

Macgregor told host Tucker Carlson that he is not surprised by the allegation, but noted that Milley – as of 8 PM ET – has yet to offer his side of the story. The colonel added that Woodward – who has written other exposes on the Trump era – has a tendency to be "somewhat flexible in interpretation" of events and quotations.

For his part, Trump has responded to the allegations, calling them "hard to believe" – but adding that if true, they constitute "treason" on the part of the U.S. Army general.

Carlson asked Macgregor whether it is as egregious as it sounds that Milley may have called Chinese Gen. Li Zuocheng without informing his boss, Trump.

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Macgregor replied that indeed Milley as Joint Chiefs of Staff chairman has no statutory authority, and therefore cannot make policy or make military decisions, but instead only advise the president who is the actual commander-in-chief – in the unique American system where the military is civilian-led and not headed by an active-duty general.

"The chairman [of the JCoS] is not in position to order anyone in the armed forces to say or do anything. He can’t do it. He is preeminently the senior military advisor to the president. That’s what he is, so in theory, before he would make such a phone call he would discuss the subject of the phone call with the president, the commander in chief," said Macgregor.

"He certainly would not do something without coordinating with The National Security Advisor and the secretary of state, because this is beyond Defense. This is a foreign policy statement that he is making. These are important things to understand."

"[Milley] violated the law, if this turns out to be true. We really need to hear from him – Congress needs to bring him over, he needs to be placed under oath and answer questions in front of the Senate about this entire affair."

Macgregor added that another aspect of the scenario is the fact the president cannot act totally independently in launching a nuclear weapon, as critics may have feared, but instead must engage in a "consultative process."

However, that process does not include Milley as JCoS chairman, but instead the Pentagon chief and the "Strategic Command".

"[That] has nothing to do with Milley – [but] as an adviser, General Milley can speak up and suggest what they should do or not do," he said.

The colonel added that Milley, who continues in his chairman role under President Joe Biden, could have resigned his post if he felt so strongly that Trump was reckless or whatever the adjective might be.

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"That does not mean he has to leave the armed forces, it means he leaves his position and someone else can be brought in. That is what you do if you feel strongly that you are dealing with someone you cannot support," Macgregor said of Milley, who has been in the military since 1980.

Later, Carlson said the allegations further embolden his view that Milley is a "dishonorable man" – hearkening back to his controversial testimony about "White rage" and other comments before Congress.

"On the other hand, we know for a fact that he was speaking in a capacity, I guess, as a political partisan to the leaders of the other party," Carlson added, noting Woodward and Costa reported that the general – while not informing Trump of his alleged contact with General Li – had spoken to Sen. Charles E. Schumer of New York and House Speaker Nancy Pelosi, D-Calif.

"He made it clear on numerous occasions that he was talking directly to [them], reassuring them that he was in control of things at the Pentagon. Plenty of people who saw that including the acting secretary of defense. That is unfortunate," Macgregor said, alluding again to the fact Milley should in theory have no statutory control over military operations.

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"I just want to make one point very clear," Macgregor told Carlson. "President Trump is not someone who is prepared to launch a nuclear strike out against anyone. That is absurd nonsense."

In closing, Carlson noted Trump was the first president since Jimmy Carter not to start a war on his watch, in contrast to allegations the Palm Beach Republican is somehow notoriously hawkish.