Barack Obama

Ahead of Obama's arrival Friday evening, large numbers of security forces patrolled in the Kenyan capital, Nairobi. Several U.S. military aircraft were spotted flying around the city. There have also been significant military attacks on Islamic militant targets in Somalia in recent weeks.

It was a striking experience for a young man — and future American president — struggling to understand how a country he had never seen and a Kenyan family he barely knew had shaped his identity.

"My name belonged and so I belonged, drawn into a web of relationships, alliances, and grudges I did not yet understand," Obama wrote in his memoir, "Dreams From My Father," about the airport encounter.

As last Monday became Tuesday in Vienna, the U.S. secretary of state picked up the telephone in his first-floor room at the ornate, 19th-century Palais Coburg and dialed the White House.

We have a deal, Kerry told President Barack Obama.

Emma Didlake's service is a reminder of the sacrifices made by those who fought in World War II or supported those who did, Obama said.

Didlake was a 38-year-old wife and mother of five when she signed up for the Women's Army Auxiliary Corps in 1943. She held the rank of private and served stateside for about seven months as a driver.

A day after the U.S., Iran and world powers announced the deal, Obama said the U.S. faces a "fundamental choice" about whether to embrace the opportunity to resolve the Iranian nuclear issue peacefully. His remarks in a White House news conference appeared aimed squarely at Congress, where lawmakers are discussing legislation to try to stop the deal's implementation.

"I expect the debate to be robust, and that's how it should be," Obama said, imploring lawmakers who are skeptical of the deal to "remember the alternative."

Under the historic accord, Iran's nuclear program would be curtailed in exchange for billions of dollars in relief from international sanctions. The agreement aims to avert the threat of a nuclear-armed Iran and another U.S. military intervention in the Middle East.