The soldiers were traveling near Ba'qubah today when a roadside bomb hit their vehicle, which then came under fire.
The attack followed the deaths of 10 U.S. Marines in an assault near Al-Fallujah, west of Baghdad.
That 1 December attack was one of the worst single incidents to hit U.S. troops in Iraq. The losses were among 14 new deaths in Iraq announced by the U.S. military yesterday.
Meanwhile, envoy Anas al-Tikriti arrived in Iraq today from Great Britain to try to secure the release of four peace activists taken hostage.
The kidnappers have threatened to kill the men -- two Canadians, an American, and a Briton -- unless all prisoners in U.S. and Iraqi detention centers are freed by 8 December.