A series of attacks on US forces in Iraq on Wednesday has left one soldier dead and at least five others wounded.
Iraqi militias are believed to be behind the attacks
A missile was also fired at an American transport plane as it landed at Baghdad airport in what a spokesperson said was possibly the first such attack during the conflict.
And in another incident, the pro-American mayor of the western Iraqi town of Haditha and one of his sons are reported to have been shot and killed.
The new spate of attacks comes as correspondents say US forces in Iraq are becoming increasingly nervous and desperate to return home.
A US spokeswoman, Sergeant Amy Abbott, said a surface-to-air missile was launched at a C-130 transport at 0845 (0445 GMT) on Wednesday but missed its target.
"I have not heard of any incident of this type," she added.
The car of Haditha's mayor, Mohammed Nayil al-Jurayfi, was ambushed as it drove through the town, about 240 kilometres (150 miles) north-west of Baghdad, Arab satellite network Al-Jazeera reports.
The BBC's Peter Greste says Iraqis working with Americans are becoming increasingly frightened about the risk to their own lives.
He says translators are worried about reprisals from the militias.
'Stayed long enough'
One soldier was killed and two injured in an explosion which hit their convoy as they travelled west of the capital, near Abu Ghraib.
At least three other US soldiers were wounded in separate attacks in Baghdad.
After the US soldier was killed early on Wednesday morning, one soldier raked the surrounding area with machine gun fire. Another soldier wept at the side of the road comforted by a colleague.
Specialist (Spc) Jose Colon, who was in a car behind the truck hit by the blast, said the dead soldier was blown out of the vehicle.
"We were just driving along when the explosion hit," he told The Associated Press. "It was very big."
Soldiers at the scene said the blast happened as a 20-vehicle convoy was passing a wrecked car abandoned at the roadside. They believe a bomb was hidden in the car wreckage.
Soldiers said the victim had recently arrived in Iraq after being stationed in Kuwait. The troops in the convoy were all reservists from a supply unit based in Puerto Rico.
Spc Carlos McKenzie said the convoy, which was on its way to a US base in the desert near Iraq's border with Jordan, did not have enough protection from more heavily armed units.
Troops in the Gulf
Start of war:
"We need more protection. We've seen enough. We've stayed in Iraq long enough," he said.
Later in the morning, at least one soldier was wounded in the al-Mansour district of Baghdad when a grenade was thrown at troops guarding a bank.
Two more soldiers are reported to have been injured - one seriously - when their vehicle exploded in the south of the capital.
The US military said it was possibly caused by a landmine, but some Iraqi witnesses said they believed the vehicle was hit by a rocket-propelled grenade.
An Iraqi child was reported to have been killed in the bank attack, and four other Iraqis wounded.
More than 30 US troops have been killed as a result of hostile action since US President George W Bush declared major combat over on 1 May.
The US in Iraq, Paul Bremer has said US-led forces will stay in the country no longer than necessary, but will see Iraq through the transition to an elected government - which could be next year.
At the start of the war there were more than 115,000 US ground troops in the Gulf alongside 26,000 from the UK.
Since then the US has increased its forces to 148,000 while the UK contribution has dropped to 11,000.