WASHINGTON (AP) — The top U.S. military officer told Congress that he knew former President Donald Trump wasn't planning to attack China and that it was his job to reassure the Chinese of this in the phone calls that have triggered outrage from some lawmakers.

Army Gen. Mark Milley, chairman of the Joint Chiefs of Staff, delivered a vehement defense of two calls he made to his Chinese counterpart, saying he was responding to a "significant degree of intelligence" that China was worried about a U.S. attack.

"I know, I am certain, that President Trump did not intend to attack the Chinese. ... And it was my directed responsibility by the secretary to convey that intent to the Chinese," Milley told the Senate Armed Services Committee on Tuesday. "My task at that time was to de-escalate. My message again was consistent: Stay calm, steady, and de-escalate. We are not going to attack you."

Milley has been at the center of controversy after reports that he made two calls to Gen. Li Zuocheng of the People's Liberation Army to assure him that the United States was not suddenly going to go to war with or attack China. Details of the calls were first aired in excerpts from the recently released book "Peril" by Washington Post journalists Bob Woodward and Robert Costa.

While Tuesday's hearing largely focused on the troop withdrawal from Afghanistan and the chaotic evacuation of Americans, Afghans and others from the country, a few senators condemned Milley for what they saw as inappropriate communications with Li.

In his most extensive comments to date on the matter, Milley said the calls on Oct. 30 and Jan. 8 were fully coordinated with the defense secretaries at the time as well as other U.S. national security agencies. And he said that such military-to-military communications are critical to prevent war between great powers that possess nuclear weapons.

The calls came during Trump's turbulent last months in office as he challenged the results of the 2020 election. The second call came two days after Jan. 6, when a violent mob attacked the U.S. Capitol in an effort to prevent Congress from certifying Biden's White House victory.

Milley said the October call was made at the direction of then-Defense Secretary Mark Esper and the second was done at the request of the Chinese and coordinated with then-acting Defense Secretary Chris Miller's office.

Asked if he spoke with the book's authors and if his remarks were "accurately represented," Milley said he spoke with Woodward and that he has not read the book but has seen press reports on it.

Sen. Marsha Blackburn, R-Tenn., asked that he provide more answers once he's read the book. She and Sen. Rick Scott, R-Fla., questioned whether Milley shared private presidential conversations with the authors.

Milley said he did not leak private conversations he had with Trump, and said he routinely speaks with the media to provide information and transparency to the American people.

Milley also addressed a call he received from House Speaker Nancy Pelosi. He said Pelosi "called me to inquire about the president's ability to launch nuclear weapons. I sought to assure her that nuclear launch is governed by a very specific and deliberate process."

He said he assured her that while the president is the sole nuclear launch authority, "he doesn't launch them alone." He said that as chairman he is part of the launch decision process.

"There are processes, protocols and procedures in place, and I repeatedly assured her there is no chance of an illegal, unauthorized or accidental launch," Milley said.

The book asserts that during the call, Milley agreed with Pelosi's statement that Trump was suffering a mental decline after the election. During Tuesday's hearing, Milley appeared to discount that, saying "I am not qualified to determine the mental health of the president of the United States."

He said that after the call was over, he had a short meeting with staff to go over the process. He also said he informed Miller of the call at the time.

"At no time was I attempting to change or influence the process, usurp authority or insert myself in the chain of command, but I am expected, I am required, to give my advice and ensure that the president is fully informed," Milley said.