Nikki Haley, former U.S. Ambassador to the United Nations, said on "America’s Newsroom" Thursday Chairman of the Joint Chiefs of Staff Gen. Mark Milley has a lot of questions to answer at a Sept. 28 Senate hearing.

"You don't have the back of the Chinese, you have the back of your president," said Haley, reacting to reports Milley called Chinese officials at the end of the Trump administration 

Haley said during her time in the Trump administration she observed that "there were multiple members of the administration that thought they knew better than the president."

TRUMP ACTING DEFENSE SECRETARY MILLER SAYS HE ‘DID NOT’ AUTHORIZE MILLEY CHINA CALLS, SAYS HE SHOULD RESIGN

"That's a very dangerous thing," Haley said.

The former South Carolina governor pointed out that although it is not unusual for countries like China and Russia to call, the question lies with why Trump would have been left out of the loop.

"There is only one president at a time," Haley said. "And for you to go and have the call with the Chinese, there's nothing wrong with that. For you not to tell the president that you had that call with the Chinese and for him not to be aware, that's the problem."

Former acting Secretary of Defense Christopher Miller, who led the Pentagon from the period after the 2020 election through Inauguration Day, said that he "did not and would not ever authorize" Chairman of the Joint Chiefs of Staff Gen. Mark Milley to have "secret" calls with his Chinese counterpart, describing the allegations as a "disgraceful and unprecedented act of insubordination," and calling on him to resign "immediately."

Haley noted that it would have been wise to double-check with the commander-in-chief first if Mark Esper, the former United States Secretary of Defense, asked Milley to have serious discussions with the Chinese. 

He "should have had a conversation with the president and said, 'we have intel that the Chinese are worried we're going to start some sort of war action. We're going to give them a call. This is what we're thinking. Are you OK with that?'" Haley said.

MILLEY SPOKESMAN DEFENDS CALLS WITH CHINA AS 'VITAL' TO 'AVOIDING UNINTENDED CONSEQUENCES OR CONFLICT'

"There are more questions than there are answers. I think we need to get answers to that. Look, everybody's suspicious of Milley when we already look at what happened in Afghanistan."

Former acting Secretary of Defense Miller went on to reference the allegations, which are included in the book "Peril," co-written by Washington Post reporters Bob Woodward and Robert Costa, that Milley made two secret phone calls, both to his Chinese counterpart, Gen. Li Zuocheng of the People’s Liberation Army. 

The book alleges that the phone calls took place prior to the 2020 presidential election, on Oct. 30, 2020, and then two days after the Jan. 6 Capitol riot, on Jan. 8, 2021.  

Fox News spoke with multiple individuals who were in the room during the two phone calls Milley had with Li. The calls, in October, were coordinated with then-Defense Secretary Mark Esper’s office. 

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"They were not secret," a U.S. official told Fox News about the calls, which took place over video teleconference. 

Fox News' Brooke Singman contributed to this report.