WILLIAM BRANGHAM: Welcome to the "NewsHour."

Defense Secretary Lloyd Austin offered a full apology today for failing to disclose his battle with prostate cancer.

The military's second in command kept President Biden in the dark when he was initially diagnosed in December and during subsequent hospitalizations.

That prompted new federal guidelines and triggered a political firestorm.

At the Pentagon today, Austin, who is 70 years old, was visibly limping as he made his way to the podium for his first press conference since the scandal broke.

LLOYD AUSTIN, U.S. Secretary of Defense: I'm recovering well, but, as you can see, I'm still recovering.

I want to be crystal clear.

We did not handle this right and I did not handle this right.

I should have told the president about my cancer diagnosis.

I should have also told my team and the American public.

And I take full responsibility.

WILLIAM BRANGHAM: The reviews of the department's notification protocols are still ongoing.

Our own Nick Schifrin was there at the Pentagon today, and he joins me now.

So, Nick, there's this long gap of almost a month between the diagnosis and Austin finding out about it and him telling the president.

How did he explain that today?

NICK SCHIFRIN: Austin today called his cancer diagnosis a gut punch, and he said that his instinct was to remain private.

But, as you point out, it was nearly a month between the time he got his diagnosis, he had his surgery, and then he had his complications, which required a second hospitalization.

And only after it became public did he tell the president.

I asked him today, what was he thinking?

This was his response.

LLOYD AUSTIN: When you're the president of the United States, you have got a lot of things on your plate.

And so putting my personal issue on -- adding to all the things that he's got on his plate, I just didn't feel that that was a thing that I should do at the time.

But, again, I recognize that that was a mistake, and I should have done that differently.

NICK SCHIFRIN: Austin said he never directed staff to withhold the fact that he was back in the hospital on January the 1st, and he claimed that there was no gap in any authorities inside the Department of Defense.

But there are still questions, William, especially the night of January 1, when he went back into the hospital.

He was taken there in an ambulance, and an aide told the dispatcher, have the ambulance arrive without any sirens.

As for informing the public, he acknowledged today he really missed a public service opportunity to tell men, especially his age, that they should screened for prostate cancer, because the fact is, the screening caught his prostate cancer in good enough time for his prognosis to be excellent.

One in eight American men, William, will get prostate cancer.

One in six Black American men will get it.

WILLIAM BRANGHAM: So that whole scandal is happening amidst the U.S. trying to decide how it's going to respond to the killing of these three U.S. soldiers in Jordan over the weekend.

What did Austin have to say about that today?

NICK SCHIFRIN: Austin called this moment in the Middle East a dangerous one.

And he reiterated that whatever U.S. military response to the attack that killed three U.S. soldiers over the weekend, that military response would not be one and done, but instead what he called multitiered.

LLOYD AUSTIN: You know, I don't think the adversaries are of a one-and-done mind-set, and so they have a lot of capability.

I have a lot NICK SCHIFRIN: President Biden has already decided amongst the targets that include Iranian-backed proxy forces in Iraq and Syria, Iranian targets in Iraq and Syria, as well as targets inside Iran itself.

And I asked Austin if Iran's operational role in the attack this weekend would be important when the U.S. administration was deciding how to respond to the attack.

He said -- quote -- "It doesn't really matter," because Iran sponsors, funds and trains these proxy groups in Iraq and Syria.

The question now is, William, of course, how the administration will punish Iran itself or just its proxies after 160 attacks on U.S. forces in the last three months across Iraq and Syria.

WILLIAM BRANGHAM: Nick Schifrin, thank you so much.

NICK SCHIFRIN: Thank you.