AMNA NAWAZ: Four months after the 9/11 attacks, the first detainees arrived at a U.S. military facility in Guantanamo Bay, Cuba.

More than 20 years later, 30 men are still there.

There's also a new debate over potential plea deals for five detainees accused of key roles in 9/11, including the alleged architect, Khalid Sheikh Mohammed, complicating the decades-long effort to permanently shut down the prison.

Carol Rosenberg of The New York Times has covered the facility since it opened, and she joins me now.

Carol, thanks for joining us.

Good to see you.

CAROL ROSENBERG, The New York Times: Good to see you.

Thank you.

AMNA NAWAZ: So, 9/11 families were notified about a possible plea deal with the U.S. military with five detainees last month.

Hundreds of families and survivors and some first responders have now sent a letter to President Biden asking him to reject the deal.

In fact, a spokesman for the group, a man named Brett Eagleson, who lost his father on 9/11, said this to Politico.

He said: "A plea deal avoids a trial.

A plea deal avoids a public reckoning.

And that's the important issue.

We cannot have the greatest terrorist attack in the history of this country fade away with plea deals for the last remaining prisoners in Guantanamo."

So, Carol, just bring us up to speed.

Where do those negotiations over possible plea deals stand?

CAROL ROSENBERG: The negotiation table is open.

The prosecution is still offering for the -- at least four of the five defendants to plead guilty in exchange for at most life in prison.

What President Biden did recently is, he rejected some conditions Khalid Sheikh Mohammed and the other detainees had put on their pleading guilty.

They wanted torture treatment guarantees and to not be held in solitary confinement.

The president said he's not signing off on those, but the prosecution is still open to a plea deal.

And the reason why is, a trial is years away.

And as they, I think, explained in their letter, the plea deal would provide what they call judicial certainty, meaning a conviction that would not be subject to appeal.

It is true they would not get a year-or-more-long trial, a parade of witnesses, but there would be a mini-trial, in which the government would present the crimes, and the defendants would have to admit to the crimes that they say the government could prove against them.

So I think there's been a little bit of misunderstanding.

It wouldn't look like the trial of the century, but it would look like a fact-finding for a jury to decide whether to give them the full life in prison or less.

AMNA NAWAZ: Carol, at the same time, we know that not everybody feels that way about wanting to reject those plea deals.

In fact, a group of children who lost their parents and grandparents on 9/11 also sent a letter to President Biden earlier this year saying they want plea deals.

They think plea deals are the only way to get accountability and to get closure.

There's a young woman named Elizabeth Miller, who's 28 years old.

She lost her dad on 9/11.

And this is what she told NPR earlier this month: ELIZABETH MILLER, Daughter of September 11 Victim: My fear is that, if we don't pursue plea deals and if the Biden administration doesn't put their full support behind this, I am 28 years old turning 29.

I'm going to be doing this advocacy until I'm 50-plus years old.

AMNA NAWAZ: Carol, if there aren't plea deals, what does justice look like for the remaining detainees at Guantanamo Bay?

CAROL ROSENBERG: Well, certainly, for the 9/11 defendants, excruciating continuation of pretrial hearings in which there is evidentiary debate and witnesses over whether the confessions the prosecutors would like to use at trial were voluntary and admissible.

The defendants weren't taken straight to Guantanamo or straight to the United States for trial when they were arrested a year and two years after the 9/11 attacks.

They were sent to CIA black sites for three and four years.

And that period has complicated the pretrial effort.

The CIA doesn't want to give up all the information.

The defense lawyers are insisting on more details.

And a judge and possibly a jury is going to have to decide which of the evidence is untainted.

AMNA NAWAZ: Carol, you know these numbers better than anyone, but I will put them up for the benefit of our audience.

That population at Guantanamo Bay has dramatically come down from near 800 people since beginning back in 2002.

Each president has transferred folks out.

President Bush transferred out about 540, President Obama about 200.

President Trump transferred out one individual to prison in Saudi Arabia.

And President Biden has transferred six so far.

Help us understand briefly, if you can, just why is it so hard to transfer out these last remaining prisoners?

CAROL ROSENBERG: Well, certainly, about 15 of them, they're not willing to give up anyways.

The government, the intelligence agencies and the prosecutors want about 15 of them, 12, 15 of them, continue to be detained as war prisoners.

The others are from countries we will not send them back to, Yemen primarily, because we think that they would become - - it would not -- Yemen does not provide the kind of rehabilitation and monitoring possibilities that this country insists on.

They need a third country to take them in and offer to monitor them, provide them resettlement and safe haven.

And, frankly, the Biden administration hasn't been able to seal the deal for more than a dozen Yemenis yet.

AMNA NAWAZ: Carol, nobody knows this story better than you.

No one's covered it more consistently than you.

As you know, folks have been saying for decades the facility needs to close.

I just wonder, as you look back on the last 22 years it's been open, how do you reflect on it, the fact that Guantanamo Bay prison is still open to this day?

CAROL ROSENBERG: The nation had a choice under Barack Obama to pick up Guantanamo and move the remnants of it to the United States or to continue to fund and run this remote, faraway prison down in Cuba.

And Congress prevented the closure that would have allowed some of these war prisoners to have been taken to the United States.

At this point, it's getting smaller and smaller.

The operation is getting smaller and smaller.

And it's very easy to forget that Guantanamo is there, which, in effect, means it's not as much a part of the national debate anymore.

AMNA NAWAZ: Carol Rosenberg of The New York Times, thank you, as always, for joining us.

We appreciate it.

CAROL ROSENBERG: Thank you.