AMNA NAWAZ: The Biden administration has determined that the Rapid Support Forces rebel group in Sudan is committing genocide.

And the Treasury has announced new sanctions for the group's leader and affiliated companies.

It's the latest escalation for Sudan, which aid groups say is facing the worst humanitarian crisis in the world right now.

She can no longer hold her son, so Zaytona Yacoub clings to the clothes he left behind.

ZAYTONA YACOUB, Displaced Sudanese (through translator): I found his body stiffened.

I carried him and ran to my neighbor, and I asked her to have a look at him.

She told me: "Your son is gone."

AMNA NAWAZ: Seven-and-a-half-year-old Zaki (ph) died of starvation.

His family, like millions, displaced by years of fighting in Sudan.

Zaytona is now among the masses mourning a loved one in this war.

Today, Secretary of State Antony Blinken declared that a genocide took place in Sudan, singling out the paramilitary Rapid Support Forces, or RSF, as fueling some of the worst violence.

In a statement, Blinken said: "The RSF and allied militias have systematically murdered men and boys, even infants, on an ethnic basis, and deliberately targeted women and girls from certain ethnic groups for rape and other forms of brutal sexual violence."

Blinken accused those same militias of targeting and murdering innocent people, escaping conflict, and preventing civilians from accessing lifesaving supplies.

Ahmed Mohammed helped to dig the graves and bury the dead near Khartoum.

AHMED MOHAMMED, Sudan Resident (through translator): Most of those people died because of disease and starvation.

RSF fighters deprived us of everything.

AMNA NAWAZ: The U.S. Treasury Department levied sanctions on RSF leader Mohamed Hamdan, also known as Hemedti, plus seven RSF-owned companies based in the United Arab Emirates.

The RSF stems from the government-backed Janjaweed militias, a largely Arab force that brutally crushed an uprising of non-Arabs in the 2000s, killing hundreds of thousands of people.

In 2004, the U.S. declared that war in Darfur a genocide.

Years later, a 2020 peace agreement was quickly undone by a coup and subsequent fighting the following year, and, by 2023 a full-blown civil war, as the RSF fight the Sudanese military for control of the country.

The war has accelerated an already dire humanitarian crisis.

Millions of Sudanese are short on food, water, and electricity, and the medical system is on the verge of collapse.

The U.S. envoy for Sudan, Tom Perriello, says some estimates suggest close to 150,000 people have been killed as a result of the conflict.

For more, we turn to Beth Van Schaack, U.S. ambassador at large for global criminal justice.

Welcome to the "News Hour."

BETH VAN SCHAACK, U.S.

Ambassador at Large For Global Criminal Justice: Thank you for having me.

AMNA NAWAZ: So, Secretary Blinken noted that, back in December of 2023, he concluded, both the RSF paramilitary forces and the Sudanese Armed Forces had committed war crimes.

He also said it was based on new information this designation of a genocide was made, that the RSF militias had committed genocide, and just the RSF militias.

What new information came your way today that you didn't have back in December of 2023?

BETH VAN SCHAACK: This war has been catastrophic on Sudanese civilians across Darfur and across the entire country.

And what we're seeing in Darfur in particular now at the hands of the RSF are targeted killings based upon ethnicity, statements in perpetrators' own words saying they want to eradicate particular ethnic groups from the region and entirely.

We see sexual violence rampant.

We see men and boys being killed, including infant boys.

So these are all indicia of genocide.

These are the types of things that prosecutors around the world will rely upon in order to infer that perpetrators are acting with genocidal intent.

AMNA NAWAZ: So, to be clear here, you saw statements of intent.

You saw the targeting of specific ethnic groups here.

And that's over the duration of the war or a particular time period in this war?

BETH VAN SCHAACK: Well, we're able to collect more information about these statements of intent and to see the conflict in the aggregate.

It's -- genocide is different from crimes against humanity and war crimes.

You have to show this special intent to destroy the group in whole or in part.

And that can be quite difficult when you don't have access to the ground.

AMNA NAWAZ: Well, as part of this new declaration now, there's sanctions, as we mentioned, from the Treasury Department against the RSF leader.

He's known as Hemedti.

Tell us about what the intended impact is there.

I mean, is this someone who has business investments or any kind of business deals with U.S. financial institutions?

BETH VAN SCHAACK: He has a huge network that he's able to rely upon, including a number of UAE-based, Emirati-based corporations, that are not only financing his activities, but also procuring weapons for the RSF.

And so these entities and wealthy individuals are participating in international markets, including the gold market, the oil market.

And so being able to sanction some of these individuals and entities make it much more difficult to tap into those financial networks.

And individuals who would want to transact business with those individuals or entities themselves may be subject to sanctions.

So it helps to contain outside forces that might be fueling the violence in Sudan.

AMNA NAWAZ: I understand reaching a declaration like this takes months of work and research and consideration.

As you mentioned, genocide has a very specific definition under that U.N. convention.

The bar here seemed to be, as you mentioned, the expressed intent to kill, the targeting of a specific ethnic group, the mass targeting of civilians in particular.

If that was the bar and it was met in Sudan, why has that bar not been met by your standards by Israel in Gaza?

BETH VAN SCHAACK: Well, every atrocity determination that the secretary does is based upon a consideration of the facts as we know them, the law that exists, and also the policy of the United States towards that particular conflict and what we're trying to accomplish in terms of the role that we're playing, whether it's bringing about a cease-fire, whether it's providing humanitarian assistance.

And so each individual determination stands on its own.

AMNA NAWAZ: But are you saying that some of these same things that you say were met here in Sudan, the expressed intent, which South Africa says in their accusation of Israel of genocide, they say that intent has been there by Israeli senior officials, the targeting of a specific ethnic group - - this is a specific ethnic group, Palestinians, who have been killed en masse in the last 14 months of war.

We know aid has been withheld.

All of these same things seem to have been met.

So, again, the question is, why hasn't that determination been made in Gaza?

BETH VAN SCHAACK: Well, we have disagreed with that characterization by South Africa at present, but we're still working very hard with the Israeli authorities and others to encourage them to make sure that their response to the horrific attacks of October 7 are directly in line with their humanitarian law, international humanitarian law obligations, and working very hard to try and bring about a cease-fire and to ensure adequate and much -- maximalist humanitarian assistance into Gaza and elsewhere.

AMNA NAWAZ: When you say you disagree with the South Africans, is that specifically on the intent that's been expressed?

BETH VAN SCHAACK: Yes.

It's on the basis for their claims under the Genocide Convention at present.

AMNA NAWAZ: There are a number of experts who will look and say you need to look at what Israel has done.

When 2 percent of the Palestinian population in Gaza has now been killed, that, to some, says intent.

You disagree?

BETH VAN SCHAACK: Well, that will go before the International Court of Justice, which has jurisdiction under that particular treaty.

And this will be the subject of litigation.

I'm sure that there will be multiple briefs put forward with various factual and legal predicates.

And so it will ultimately be for the judges to decide.

AMNA NAWAZ: Back to Sudan for a moment, is there any concern by you or your colleagues that the incoming administration could have a different view and possibly reverse this designation?

BETH VAN SCHAACK: Well, it's difficult to reverse a designation, because it is based upon such a strong basis of fact.

We have an enormous quantity of information that we rely upon, sources that we develop internally, but also open sources that other NGOs, the press, others have accumulated.

And so we don't -- the secretary doesn't stand up and say something constitutes a genocide lightly.

It's a very rigorous process.

And so I'm sure that the incoming administration can review the packages of material that went into this determination and will be convinced that this meets the standard of genocide.

AMNA NAWAZ: That's the U.S. ambassador at large for global criminal justice, Beth Van Schaack.

Thank you so much for your time.

BETH VAN SCHAACK: Thank you for covering this issue.