AMNA NAWAZ: Today, in the U.N. Security Council, the U.S. said that famine has -- quote - - "likely descended in Sudan" and warned that indiscriminate attacks in the capital of Sudan's North Darfur region must stop.

El Fasher was home to more than 800,000 internally displaced people before it came under siege by rebel paramilitaries.

Already, Sudan was home to the world's largest displacement and hunger crises.

And, as Nick Schifrin reports, El Fasher has become a symbol of the country's suffering.

NICK SCHIFRIN: In Sudan's north, what was once a sanctuary is now under siege.

The road to El Fasher, Sudan's last major city that hasn't fallen, is a battleground, targeted by the rebel paramilitary Rapid Support Forces, or RSF, who've been accused of ethnic cleansing, on the other side, Sudan's Armed Forces and its allies also accused of war crimes for bombing villages.

And the fight tightens the noose around the most vulnerable.

El Fasher was home to one of Sudan's final safe havens.

And, today, the country's largest group of the displaced are at threat again.

NATHANIEL RAYMOND, Yale School of Public Health: In approximately one month of fighting, we have seen absolute catastrophe in El Fasher.

NICK SCHIFRIN: Nathaniel Raymond is the executive director of the Humanitarian Research Lab at the Yale School of Public Health.

His team documents war crimes evidence through videos, open-source data, and satellite imagery.

He says El Fasher is dying.

NATHANIEL RAYMOND: In one-nine day period alone, almost 200 football fields' worth of damage to civilian infrastructure was recorded.

I can't overemphasize for those watching this broadcast that the speed of destruction by fighters on the ground is almost unparalleled.

NICK SCHIFRIN: Satellite images show dozens of villages on El Fasher's outskirts burned, refugee camps devastated.

And the U.N. says El Fasher's sole hospital that could perform surgeries has been looted and is shut down.

The main targets are non-Arabs, as they were during Darfur's genocide in the '90s by the Rapid Support Forces precursor, the Janjaweed.

NATHANIEL RAYMOND: Dr.

Rapid Support Forces are already engaged in ethnically targeted attacks within El Fasher.

If the Rapid Support Forces capture El Fasher, they will be able to make Darfur their home base of operations to fight for control of Sudan for years to come.

EDEM WOSORNU, U.N. Office for the Coordination of Humanitarian Affairs: Forty hundred and thirty days into this conflict, the level of human suffering in Sudan is intolerable.

NICK SCHIFRIN: Today, at the Security Council, the U.N. warned that two million Sudanese are at risk of slipping into catastrophic hunger.

EDEM WOSORNU: Every day that we wait for funding to come, more lives are at risk.

NICK SCHIFRIN: Outside countries have ignored U.S. and U.N. demands and sent both sides weapons.

NATHANIEL RAYMOND: Without these foreign backers, the war would have ended quickly.

The war is now into its second year because of arms shipments from multiple outside actors.

NICK SCHIFRIN: Last week, the Security Council passed a resolution demanding the end of the siege of El Fasher, called on countries to respect arms embargoes, and not fuel the conflict by providing weapons.

But the resolution has no enforcement mechanism.

We now turn to Dr. Yasir Elamin, president of the Sudanese American Physicians Association, who just left Sudan last week and joins us now from Cairo.

Dr. Yasir Elamin, thank you very much.

Welcome back to the "NewsHour."

What did you see when you were there?

How dire is the humanitarian crisis?

DR. YASIR ELAMIN, President, Sudanese American Physicians Association: I visited a hospital in Omdurman, west of Khartoum, where patients with -- or children with malnutrition are being treated.

And I saw three children sharing bed.

Those children are being treated for malnutrition.

They are skin and bone.

They are just a testimony to the acute hunger that Sudan faces now.

I have also witnessed the extreme limited resources that hospitals suffer from.

And please remember that almost 60 percent of Sudan hospitals are nonoperational at the moment.

NICK SCHIFRIN: So what you're seeing, what you're highlighting is two aspects, as you said, both the hunger and also the inability for doctors and hospitals to provide the medicine that's needed.

Each of those cases, you and I talked about when you were on the broadcast last year.

Has it gotten much worse?

DR. YASIR ELAMIN: I think it has.

Again, make no mistake, this is a manmade crisis.

This is not due to a natural disaster.

This is a decision by the SAF and by the RSF.

(CROSSTALK) NICK SCHIFRIN: SAF, the Sudanese Armed Forces, and RSF, Rapid Support Forces, the rebel paramilitary group.

DR. YASIR ELAMIN: Correct.

This is my second time that I have been to Sudan since the war erupted.

And I could notice the worsening of the humanitarian crisis.

And, also, I could witness the extreme sense of lawlessness.

One of the things that I witnessed is that a lot of civilians are now carrying guns, carrying Kalashnikovs.

When I went last year, there was a sense that there was still some sort of law, some sort of order, some sort of army being so strong and being able to control things.

I have lost that sense when I visited Sudan last week.

NICK SCHIFRIN: One of the hot spots that we have highlighted today is El Fasher in Darfur.

What is the impact of the fact that there's really only one health care facility available?

DR. YASIR ELAMIN: Well, it's clearly a complete disaster, for a simple reason this is a war zone.

So -- and there is indiscriminate bombing both by SAF and by the RSF.

So, there is great need for hospital services, let alone the other normal, ordinary disease that the population would have.

El Fasher has been a safe haven for hundreds of thousands of people who fled RSF.

And the worry is, if RSF will take -- were to take the city, that there may be an ethnic cleansing there, or there may be widespread violence and massacres happening inside El Fasher.

So that's why El Fasher is particularly worrying.

And the lack of health services there is even more worrying, especially when we may be faced by a crisis very soon.

NICK SCHIFRIN: And, finally, Dr. Elamin, how much has this war been defined by gender-based violence?

DR. YASIR ELAMIN: You know, Sudan has known gender-based violence, but the scale of the gender-based violence in this war has been unprecedented.

One of the very brutal aspects of this war is the amount of women, young girls in some cases, that were raped.

When I was in Omdurman, I have heard horrible stories from physicians who've treated rape victims.

We're talking about victims who are 16 years old, 15 years old.

It's now something that's very routine when the RSF, in particular, takes over a place, that mothers and elderly try to hide their younger sisters and daughters.

Clearly, the majority of reported cases by credible sources and, certainly, from talking to the physicians that I met in person in Omdurman now, most of the cases have been committed by RSF.

NICK SCHIFRIN: Dr. Yasir Elamin, president of the Sudanese American Physicians Association, thank you very much.

DR. YASIR ELAMIN: Thanks for having me.