GEOFF BENNETT: The U.N. warns that the humanitarian crisis in Gaza is growing more acute.

In Southern Gaza, a quarter of the population faces catastrophic levels of food insecurity.

In Northern Gaza, nearly one in three children are severely malnourished.

Nick Schifrin speaks to the U.N.'s top humanitarian official about Gaza, Sudan, and what he calls one of the worst years for humanitarian crises.

NICK SCHIFRIN: The U.N. says every single one of Gaza's 2.2 million or so residents need food assistance and the threat of famine is looming.

One of the leading officials dealing with this crisis is the U.N.'s undersecretary-general for humanitarian affairs and emergency relief coordinator, Martin Griffiths, who will be stepping down soon after a 50-year career on humanitarian and conflict work.

Martin Griffiths, thanks so much.

NICK SCHIFRIN: Welcome back to the "NewsHour."

The executive director of the World Food Program, Cindy McCain, recently said that Northern Gaza is in -- quote -- "full-blown famine."

Do you agree?

MARTIN GRIFFITHS: I would agree with her in substance, in the sense that there is a very, very, as you know, stringent technical process, independent of the U.N., by the way, to identify when famine exists.

But we know from Gaza, we know from elsewhere that don't wait for the declaration, official declaration, to know that people are dying of hunger, kids are dying of malnutrition.

NICK SCHIFRIN: Today, the U.S. military announced that a floating pier designed to deliver humanitarian aid to Gaza has been attached to Gaza.

They have hundreds of tons of aid ready for delivery, thousands more tons in the pipeline.

How much of an impact could this kind of thing have?

MARTIN GRIFFITHS: It's very helpful.

We have always said that any way to get more aid in should be welcomed.

We have also said, as you know, that land access routes tend to be more efficient and can go to scale.

We in the U.N. and the World Food Program are ready and prepared to help distribute that aid coming in off the floating pier in the days to come to Gaza.

NICK SCHIFRIN: There are also security concerns about the pier.

U.N. officials who've been working to prepare the pier had to take cover when the area came under fire.

How serious, from your perspective, are the security concerns for the U.N., for the World Food Program, who's going to be part of this?

MARTIN GRIFFITHS: I think they're very serious.

For the moment, the risk level is one that we can go with on the basis that no aid is coming in the other areas.

So we're looking at being able to fulfill our task of distribution internally and hoping that we can get the right people to help us on the beach to get aid to the World Food Program.

NICK SCHIFRIN: Who are those right people?

MARTIN GRIFFITHS: Well, I think we're talking about contractors, as well as maybe some U.N. staff.

That's where the final stages of making sure that we have got an operation that we are happy, in terms of accountability, as well as risk levels for anybody who's going to be there.

NICK SCHIFRIN: There have been occasions where Hamas has diverted or stolen the aid.

How do you prevent that from happening?

MARTIN GRIFFITHS: Where that's happened, we have negotiated to get that aid back.

And, as far as I'm aware, in all cases, that has succeeded.

We need to get all deliveries safely delivered.

Aid is going in through the north, as you know, Nick, through Erez.

I think 54 trucks got in there yesterday.

NICK SCHIFRIN: The Erez crossing in the north recently opened by Israel.

MARTIN GRIFFITHS: Recently opened, most welcome, by the way.

But on the whole, that aid is going to the needs, which are very extensive, in the north.

Getting aid into the south is incredibly difficult because both of the main crossing points are closed or difficult to get through.

NICK SCHIFRIN: Since the Israeli military launched an operation the ground into Rafah, specifically at the border crossing between Rafah and Egypt, that border has been closed.

Israel blames Egypt for blocking aid.

Egypt blames the Israeli military operation for destabilizing the border.

Why do you think not enough aid is getting through that border?

MARTIN GRIFFITHS: Because it's closed and because Kerem Shalom, the other border crossing, is also a place of great difficulty to get any trucks in.

Added to that, Nick, of course, is the fact that, without fuel inside, it doesn't matter.

You can't move.

You can't move the trucks.

Our stocks inside Southern Gaza of food and other items are more or less done, finished.

We know that there are no more tents yet for people to go to.

There's 600,000 people who moved in the last couple of weeks.

We know that medical supplies may have three weeks.

We know that food in the market is about to run out.

There's no good news about what's happening in Rafah.

NICK SCHIFRIN: As you know, the Israeli government has remained concerned about Hamas infiltration.

And the Israeli military this week said that drone footage shows armed men standing next to U.N. vehicles at a U.N. compound in Rafah.

How does this happen?

And what can the U.N. do to prevent it?

MARTIN GRIFFITHS: Well, I think UNRWA has reacted to that report and is looking into the factual basis.

When did this happen?

Where did this happen?

How did this happen, if it did?

So, until we have got the facts, I'm not going to comment.

NICK SCHIFRIN: After Israeli missiles killed seven World Central Kitchen workers, Israel said that it would improve coordination with humanitarian organizations, including by opening up a new coordination center.

Has Israel done enough to answer the concerns of the U.N., the U.S., and international organizations, especially since that incident?

MARTIN GRIFFITHS: I have just been learning of some promises of progress on that very issue of embedding a U.N. staff member from my own office, indeed, with Southern Command to make sure that we are clearly aware of the trajectory of the conflict and are able to guide our humanitarian operations accordingly.

And I just hope this is going to work.

NICK SCHIFRIN: Let me move you to Sudan, which is the world's largest displacement crisis, one of the world's largest food crises.

Yesterday, the U.N. special envoy to Sudan said the Sudanese people were trapped in -- quote -- "an inferno of brutal violence."

Can famine in Sudan be prevented?

MARTIN GRIFFITHS: Yes.

But will it be prevented?

I don't know.

Five million people at risk of famine.

I'm not aware of that number ever having been at that level of risk.

We need the militaries of both sides, of all sides to give us access to get our convoys through, to get our aid through to the people.

It's the trajectory of the war and the commanders on the ground who are not giving us the access that we need.

NICK SCHIFRIN: And, finally, Martin Griffiths, if I may take a moment to step back, we haven't even talked about Afghanistan, Ukraine, Yemen.

I wonder how you look at this year and this moment after, as I said at the top, a nearly 50-year career focused on humanitarian and conflict aid.

MARTIN GRIFFITHS: Well, I do think it's as bad as it's ever been, and I think it's a year of broken promises, isn't it?

The promises that the world's leaders made these recent decades, these promises are left at the entrance and parked there.

But we still have, across cultures, across communities, across the world -- and I see it in my work -- the depth of humanity of ordinary people, which has not changed.

There's no change in these essential values.

What there is a change in is the leadership that we suffer from, I'm afraid, which don't listen to these straightforward pleas, which all of us, all of us believe in.

We all want a better future for our children and our families, right across the world.

NICK SCHIFRIN: Martin Griffiths, undersecretary-general of humanitarian affairs and emergency relief coordinator, thank you very much.

MARTIN GRIFFITHS: Thank you very much, Nick.

Appreciate it.