By Jerry Norton

WASHINGTON (Reuters) - President Barack Obama on Tuesday awarded the Medal of Honor for gallantry to Army Staff Sergeant Salvatore Giunta, the first living recipient of the top military honor for a post-Vietnam era conflict.

As a rifle team leader in Afghanistan in 2007, Giunta "exposed himself to withering enemy fire," his medal citation said, to pull a comrade back to cover when a Taliban ambush in Afghanistan split up his squad.

Later, while trying to link up with the rest of his squad, Giunta noticed two insurgents carrying away a fellow soldier.

"He immediately engaged the enemy, killing one and wounding the other (and provided) medical aid as his squad caught up and provided security," the citation said.

In his speech at the White House ceremony -- attended by Giunta's combat comrades, top military brass and earlier Medal of Honor winners -- Obama had high praise for the soldier's courage and leadership.

He said Giunta's heroism showed he took the advice of a team leader who told him, "You've just got to try to do everything you can when it's your time to do it."

Saying he was going "off-script," Obama added, "I really like this guy."

He said Giunta was "as humble as he is heroic," and that after meeting the sergeant and his family, "you are just absolutely convinced this is what America is all about."

Giunta, 25, a native of Clinton, Iowa, has been quoted as saying of the night battle where he won his medal that there "were more bullets in the air than stars in the sky. ... They're above you, behind you, below you."

In brief comments after the ceremony, Giunta said that as much of an honor as the medal was, he would give it back in an instant in exchange for the lives of friends who died fighting in Afghanistan.

The Medal of Honor is the highest award for valor in action against an enemy force that can be given to an individual in the U.S. Army. Although there have been a handful of other Medal of Honor winners from the Afghanistan and Iraq wars, their awards were posthumous.

There has been some criticism from veterans and others of what they say is a scarcity of Medal of Honor awards compared with other conflicts despite outstanding acts of bravery, and the lack of new living recipients.

(Editing by Jonathan Oatis and Peter Cooney)