Robert Costa: Gen. Mark Milley "was not going rogue" with China calls

Washington Post journalist Robert Costa on Monday said in an interview with ABC's "Good Morning America" that Joint Chiefs Chairman Mark Milley "was not going rogue" when told his Chinese counterpart that the U.S. would not launch a surprise attack.

Driving the news: President Biden last week expressed "great confidence" in Milley after excerpts released from Costa and Bob Woodward's book "Peril" revealed calls where Milley admits he would let China know ahead of time if former President Trump decided to attack.

Catch up quick: Milley said last week that his actions were "perfectly within the duties of his job" and that such conversations are "routine."

What they're saying: "What chairman Milley was trying to do, as we show in the book, was contain a national security emergency," Costa said, adding that while Milley did not believe Trump "wanted to go to war," the Chinese were "highly alarmed" after the Jan. 6 Capitol riots.

• "While these calls with General Li were held on a top-secret back channel, they were not secret. This was not someone who was working in isolation. He was reading people in in the national security community."
• "He was not going rogue. He was reading people in throughout the national security and military community trying to contain a situation and a president he believed was in serious mental decline."

Trump and other Republicans called Milley "treasonous," saying that the general subverted the military chain of command, but Woodward said that Milley's actions were "not at all" treasonous because he did keep the national security community informed.

What to watch: Milley will testify at a Sept. 28 Senate Armed Services Committee hearing, where he will likely field questions on his actions during the final days of the Trump presidency.

Go deeper: Mark Milley's crisis