A military spokeswoman said on Tuesday that the soldier's nationality was unclear.
"I assume it was an American but we still need to confirm this," she said.
Earlier, military officials announced that an American soldier had been killed and another wounded in the northern Iraqi town of Tikrit on Monday.
Tikrit, 180km north of Baghdad, is the scene of frequent attacks against occupation forces.
A US military convoy also came under rocket-propelled grenade attack in the city of Samarra.
And in the city of Baquba, occupation troops raided a number of homes, confiscated weapons found with residents and arrested a number of Iraqi civilians.
A US patrol was ambushed late on Monday in al-Qaim city near the Syrian border, leaving two vehicles damaged, witnesses told Aljazeera’s correspondent.
A US military spokesman also said that three grenades had been dropped in central Baghdad where occupation forces are based.
Meanwhile three judges have been targeted in separate incidents across the country.
Ismail Yusuf was fatally shot early on Tuesday outside his Mosul home. He was a deputy to the head of the appeal courts in the Naynawa province.
Occupation forces have yet to
bring security and stability to Iraq
"He has no enemies. He wasn't responsible for a criminal court. We thought they might be after his car but he didn't even have it with him at the time," said Saad Hamid, a police officer who worked at the same court with Yusuf.
His wife also said she had no idea why her husband was targeted.
On Monday, the head of an Iraqi court who was investigating members of ousted Iraqi President Saddam Hussein's Baath Party was abducted and killed in the southern city of Najaf.
And another judge was shot dead by US soldiers after the vehicle he was riding in came under fire in the northern city of Kirkuk.
His cousin, who was injured in the incident, said the soldiers shot at the car as they were driving by, late on Monday.
The US soldiers were apparently lying in ambush for suspected attackers in one of the city's neighbourhoods, 225km north of Baghdad.
In other reports, at least three Iraqi civilians were killed and four others wounded after a bomb exploded near a hotel in the city of Karbala, 110km south of Baghdad.
A local hospital official said on Tuesday that the blast occurred late on Monday near the Baratha hotel behind al-Mukhayam mosque.
It was not immediately clear if the bomb had been planted inside or outside an empty building near the hotel, said a spokesman for the Polish-led division of occupation forces, which patrols Karbala.
The office of the Shia cleric Muhammad Taqi al-Mudarrasi also came under attack, but there were no further details, reported our correspondent in Iraq.
Rival Shia groups have fought in
Karbala, leaving casualties
Karbala was the scene of high tension between Shia groups in mid-October, when supporters of Ayat Allah Ali Sistani prevented backers of anti-occupation cleric Muqtada al-Sadr taking control of the Husayn and Abbas mausoleums.
At least one person was killed in armed clashes between the rival groups.
Meanwhile, Spanish Foreign Minister Ana Palacio said Madrid was temporarily withdrawing its diplomatic staff from Baghdad because of the extremely complicated state of affairs in the country.
Palacio said they would return "soon". The only Spanish diplomat who would remain in the country's mission would be the charge d'affaires Eduardo de Quesada.
Three Spaniards have died in Iraq in recent weeks.
Japan to deploy
Meanwhile, Japan's government has decided to send an advance team of 150 Ground Self-Defence Force (GSDF) members to the southern Iraqi city of Samarra by mid-December, a news report in Tokyo reported.
The government will officially approve a basic dispatch plan as early as 14 November, the Nihon Keizai Shimbun newspaper said, citing government sources.
The advance team will set up a base prior to the dispatch of the main unit of 600 to 700 personnel in January.
The GSDF is discussing the possibility of providing electricity to hospitals built with Japanese aid and building water supply infrastructure.