President Obama today announced a $3 billion private sector pledge to support agriculture and help feed Africa's starving populations, saying the U.S. has a "moral obligation to lead the fight."

"When tens of thousands of children die from the agony of starvation, as in Somalia, that sends us a message we still got a lot of work to do.  It's unacceptable.  It's an outrage.  It's an affront to who we are," the president said at the Symposium on Global Agriculture and Food Security in Washington.

Arguing that food security is a moral, economic, and security imperative, Obama urged the world's biggest economies to fulfill their promises to aid the cause financially. The president said additional nations and non-governmental organizations need to "step up and play a role" because government cannot solve the problem alone.

The new shared commitment, which Obama outlined today, aims to raise 50 million people out of poverty over the next 10 years.

Obama also pushed back against criticisms that the new private sector alliance is a way for governments to shift the burden. "As president, I can assure you that the United States will continue to meet our responsibilities so that even in these tough fiscal times, we will continue to make historic investments in development," he said.

The president spoke to an eclectic crowd, including singer and activist Bono, celebrity chef Jose Andres and a host of African leaders, in his speech kicking off this weekend's G8 summit.