DAMASCUS -- This past week, the battle for Raqqa intensified. Forces backed by the U.S. miltary are trying to drive ISIS out of its stronghold in Syria.

Meanwhile, CBS News visited workers with the World Food Programme who are on the frontlines trying to get food to millions of people in need.

In a Syrian warehouse, they're preparing for the assault on Raqqa: There's sugar, salt and lentils.

"At the moment, we are supporting about 160,000 people already that have fled Raqqa from the fighting," says Jakob Kern, the country director of the U.S.-backed World Food Programme in Syria.

The World Food Programme is preparing for the assault on Raqqa. CBS News

Kern is planning for 200,000 more to flee.

To the WFP, Kern says, an assault on Raqqa means "hundreds of thousands of people moving."

Hundreds of workers -- all displaced themselves -- are working for the WFP. They pack rations to feed as many as 1.5 million families a month. It's a different diet from what they would be distributing in South Sudan.

"It's a diet that's reflecting the needs of the people -- like chickpeas -- hummus is a staple food here," Kern says.

This is about preventing hunger, of course, but it also preventing another crisis: Migration. As those who are fed here in Syria are less likely to move and cross borders in search of food.

"If you know as a family you get your monthly rations every month, you don't move," Kern says.

More than half of Syria's population has been displaced and Kern says getting food to them is complicated, with almost two dozen different armed groups fighting each other for power.

"It's probably the most complex operation in terms of access and who is controlling what," Kern says.

They're only feeding about 4 million of the 7 million in need.

But these rations are key to keeping Syrians alive and keeping them here to ultimately rebuild their country.