The US says it has found the bodies of two soldiers who went missing, feared abducted, from the Iraqi town of Balad on Wednesday.
The First Armoured Brigade had been on patrol in Baghdad
The two men had vanished with their vehicle, weapons and gear. Blood had already been found at the scene.
The news follows an overnight attack on a US First Armoured Division convoy in Baghdad which killed one soldier and wounded four others.
These are the latest in a series of strikes against US targets and brings the number of coalition troops killed in hostile action since the end of the conflict to 30.
The BBC's Peter Greste in Baghdad says the coalition is concerned that anti-US elements may also be planning attacks on soft targets such as United Nations staff and aid workers.
The bodies of the two men, Gladimir Philippe and Kevin Ott, were found 32 kilometres (20 miles) north of Baghdad.
The first clear message that we have to take out of here is
that this war is not over
A senior military official told reporters: "The first clear message that we have to take out of here is
that this war is not over. I think that is pretty clear to all
Since end of hostilities:
Killed in combat:
US - 24, UK - 6
US - 39, UK - 4
Another officer, Lieutenant General Ricardo Sanchez, said that those carrying out such attacks were the remnants of the Baath Party trying to regain control.
"That's not going to happen," he said.
However, in the past three days alone, incidents have included:
On Tuesday, six British military policemen were killed in southern Iraq after trouble erupted during weapons searches.
- A US soldier reportedly shot in the face while shopping in Baghdad
- One American military policeman killed while investigating a car theft near the southern town of Najaf
- Clashes south-west of the Iraqi capital that left a US soldier dead and eight wounded
- Assailants blowing up a US military vehicle with a roadside bomb
- A rocket-propelled grenade attack on US vehicles travelling towards the airport, killing an Iraqi driver.
- Demolition of an oil pipeline
Five hundred soldiers patrolled the town of Majar al-Kabir on Saturday for the first time since the killings, in what they described as a "show of teeth".