AMNA NAWAZ: Today, U.N.-backed human rights investigators accused both sides in the Sudanese civil war of war crimes and advocated for an independent and impartial force to protect civilians.

As a series of reports that we have presented here on the "News Hour" in recent weeks have shown, the area is devastated, with more than 10 million people displaced, millions hungry, and tens of thousands killed.

Nick Schifrin speaks with a U.S. diplomat working to address what's become the world's largest humanitarian crisis.

NICK SCHIFRIN: Amna, the civil war erupted more than 500 days ago between the Sudanese Armed Forces and the paramilitary Rapid Support Forces.

Today's call from those U.N.-backed investigators reflects the desperation to help civilians caught in the middle, especially after U.S.-backed peace talks in Geneva failed to end the fighting.

I'm joined now by Tom Perriello, U.S. special envoy for Sudan.

Tom Perriello, thanks very much.

Welcome back to the "News Hour."

As I have just mentioned, the Geneva talks did not create a pathway to peace.

So what's next?

TOM PERRIELLO, U.S. Special Envoy for Sudan: Well, first of all, we were able to have a great deal of success opening up several of the humanitarian supply routes, where over a million people are facing starvation.

Over 20 million are facing acute hunger.

Over eight million pounds of food have moved, 3,000 tons last week into areas that have not seen emergency food distribution for four months.

So, on the issues of humanitarian access, we were able to make significant progress, thanks to President Biden and Secretary Blinken giving the go-ahead to go forward with the talks.

On protection of civilians, where we have seen horrific atrocities from both sides, we were able to get the first code of conduct commitment from the Rapid Support Forces.

We have much more to be done on both humanitarian access and civilian protection.

And, ultimately, of course, the goal is a cessation of hostilities.

NICK SCHIFRIN: So how do you end this war next?

Do you try the same approach that you have had already, try and get the Sudanese Armed Forces, which did not show up in Geneva, and the Rapid Support Forces together again, as you have been doing for many months, if not longer than that?

TOM PERRIELLO: We built a team of partners from the region, along with the African Union and United Nations, that were able to be working with both the RSF and the army on really, really important, lifesaving steps to try to address this famine and civilian protection.

That's why I think we're able to build this larger diplomatic coalition to try to push for peace.

NICK SCHIFRIN: You're describing, basically, taking the same steps you already have, but, with all due respect, they have not worked.

As we have said, the Sudanese Armed Forces did not show up in Geneva.

You have had previous talks in Jeddah.

Can you focus on some of the external actors that are fueling this conflict?

Can you get the UAE to stop sending weapons to the RSF?

Can you get Egypt to stop supporting the Sudanese Armed Forces?

Can you get the actors that have been trying to put their thumbs on the scale to stop doing so?

TOM PERRIELLO: We're pushing hard to extend the arms embargo for all of Darfur.

We believe that not only needs to be extended, but we need to see greater enforcement.

The United States continues to raise the costs on those individuals that are committing atrocities on both sides, as well as some of the businesses that are aiding and abetting in that effort.

We're trying to build more partners coming in who can be part of doing that.

NICK SCHIFRIN: Do you have any leverage at all over external actors, who I mentioned before many of whom are U.S. partners, when many of those capitals are hedging two months before the election?

TOM PERRIELLO: Yes, we have been very clear that we call on all the external actors to stop fueling this war, stop sending in more arms, start to be partners in the humanitarian relief, the civilian protection and the peace efforts.

We will continue to lead on those efforts.

NICK SCHIFRIN: You have described a lot of actions the U.S. has taken, but have you threatened sanctions on the leadership of the two sides, General Burhan, the head of the Sudanese Armed Forces, General Hemedti the head of the Rapid Support Forces, as many experts have asked you to do?

TOM PERRIELLO: Yes, we have continued to increase the sanctions on both SAF and RSF leaders.

We have in some cases made those explicitly related to issues, for example, atrocity prevention.

We will continue to have that be a central part of this strategy as we look to raise the costs of those that are imposing the suffering on the Sudanese people.

NICK SCHIFRIN: You mentioned the crossing, Adre, between Chad and Darfur.

The agreement to get aid across that crossing only lasts for three months.

How are you going to extend it?

TOM PERRIELLO: Well, we absolutely want to continue to show that this is a lifesaving effort, that it is something the Sudanese people want and are appreciative of those leaders inside and outside the country that are helping to get food and medicine into these famine-stricken areas.

We believe if we can continue to show those results, we will be able to extend these efforts going forward.

But we have a lot of people to reach that have not yet been reached since these reopenings.

NICK SCHIFRIN: As I said at the top of the segment, U.N. backed human rights investigators called today for a -- quote -- "independent impartial force" to protect civilians, of course, force being the operative word there.

That could include boots on the ground.

Is that an idea you endorse?

TOM PERRIELLO: I think there's an understanding that, as you said before, we can't just keep doing the same things and expecting a different result.

The scale of this crisis, first and foremost, is being imposed on the people of Sudan, but also increasingly on the region.

And I think the recommendations coming out of the U.N. report are extremely important and timely as we head into the U.N. General Assembly and should absolutely consider them and build support for a wide range of approaches to civilian protection and other things that can help end the war.

NICK SCHIFRIN: Let me read you a statement by the deputy chairman of the Sudanese Sovereign Council, Malik Agar, to my colleague Leila Molana-Allen during her recent trip to Sudan.

Quote: "The U.S. administration, they have never come here.

We have an envoy who's never put a leg in Sudan.

If you're serious to solve a problem somewhere, why don't you come and meet the president in this country?

Why don't you meet us in our country?

But this is not happening."

TOM PERRIELLO: Well, I have traveled to Sudan before, and I traveled to Adre earlier, tried to come to Port Sudan, but was blocked by the government in the early parts of my tenure.

More recently, we put a trip together that our diplomatic security team said would require me to just be at the airport.

We communicated that.

They rejected that offer, and we completely respected them rejecting that offer.

But every week, I'm meeting with Sudanese people from all 18 states, hundreds and hundreds of Sudanese that I meet with virtually each week, as well as thousands from the refugee and diaspora community.

So we will continue to meet every day, every week with the Sudanese people.

And, hopefully, that will involve a trip to Port Sudan sometime soon.

NICK SCHIFRIN: Tom Perriello, thank you very much.

TOM PERRIELLO: Thank you, Nick.