The policemen were killed when their patrol came under attack on Thursday night in a Baquba suburb, north of Baghdad.
The other three Iraqis were killed on Friday in the town of al-Riyad near Kirkuk when an armed fighter tried to break into the governorate main building, the Kirkuk police chief said.
The two US soldiers were killed in separate attacks.
One soldier was killed by a roadside bomb in Baghdad on
Friday morning and another, a marine, died in an attack west of the capital on Thursday.
Also on Friday, a US convoy was hit by a blast on a highway north of Falluja.
Our correspondent said occupation troops quickly cordoned the area and launched a hunt for those behind the attack. No casualties among the soldiers were reported.
Japan's army chief of staff, in the meantime, made a stealthy visit to southern Iraq to meet his troops based there.
"I am relieved to see that all personnel are safe"
General Hajime Massaki, chief of staff for Japan's Ground Self-Defence Forces
Japan, one of Washington's closest allies in Asia, has sent troops on a non-combat mission to Iraq in the nation's biggest and riskiest overseas military mission since World War Two.
General Hajime Massaki, chief of staff for Japan's Ground Self-Defence Forces, as the army is known, visited their camp in the southern city of Samawa, a Japanese official said.
"I am relieved to see that all personnel are safe," Massaki was quoted as telling a news conference at the camp.