In Baghdad, on his last stop before returning to the United States, Biden visited with U.S. troops at Camp Victory.
He said the United States will end its military involvement in Iraq responsibly, leaving behind a country that is worthy of the sacrifices "that so many of your brothers and sisters have made."
The United States ended its combat mission in August, leaving behind about 50,000 troops who remain mostly in an advisory role and for training.
Throngs of Iraqis took to the streets of the Shiite holy city of Najaf following Friday prayers calling on U.S. forces to leave the country, the Voices of Iraq news agency reported
Najaf is home to anti-American Shiite cleric Moqtada Sadr, who returned to Iraq last week after living in exile in Iran. He fled Iraq in 2007 after U.S. forces descended on his supporters following post-invasion guerrilla war in the Sadr City slum of Baghdad.
Sadr in a speech last weekend called on his followers in Najaf to speak out against what he says is the American occupation of Iraq.