Some 4,800 cadets from four military academies in Iraq have graduated in a ceremony that underlines what U.S. officials say is the growing self-sufficiency of Iraqi forces.

The ceremony in Baghdad on Monday was attended by Gen. David Petraeus, the top American commander in Iraq. Petraeus told the cadets that Iraq needs less help from the U.S. military but promised that the United States remains ready to assist when needed.

Violence in Iraq is at its lowest level in four years, but deadly attacks continue.

Police in Baghdad say assailants in a speeding car threw a grenade at traffic police on Monday, killing three people and wounding 13. In a separate attack in the capital, gunmen killed two members of a Sunni force allied with U.S. troops.