The last two weeks have been the bloodiest yet for US soldiers in Iraq since the fall of Saddam Hussein. Iraqi deaths are much harder to track, but an Associated Press estimate puts the total since 1 April at 880.
April's casualty count for US soldiers has spiralled to 87, the highest for any month since the war began.
Nearly all the deaths have been in hostile incidents in two weeks which have seen major battles with both Sunni and Shia insurgents.
Most of the US soldiers have been killed in attacks on road convoys, firefights in the Sunni-dominated towns of Falluja and Ramadi and battles in and around Baghdad.
US marines load the body of a colleague into a truck
The figure of 880 Iraqi deaths was compiled from statements from US military officials and Iraqi police and hospitals.
Sources from Falluja's hospitals have estimated that 600 Iraqis died during a major US offensive against fighters there last week. According to an Iraqi official who has negotiated with insurgents in Falluja, about half of the Iraqis killed were women and children. This figure is impossible to verify.
Marine Lt Col Brennan Byrne has told AP that most of the dead are "military-age men".
Other US officials say it is not possible to give an exact civilian death toll, but troops are taking "great care" in their operations.
The number of wounded American troops has also spiralled.
More than 540 have been injured in the last two weeks - well above any monthly total since President George W Bush declared major combat over on 1 May 2003.
Even only halfway through April, the number of US deaths is already higher than its previous post-war peak of 82 in November, when a wave of insurgent bombings and attacks also pushed up casualty figures.
When non-US coalition soldiers are included, however, the death toll for November remains higher - 110 - than that for April.
The most US troops killed in a two week period at the height of the war was 94.
The total of American soldiers killed in Iraq is now 686. More than three-quarters of these have died since major hostilities ceased.
Just over a quarter of the casualties have died in "non-hostile" events such as accidents involving vehicles or munitions.
Lt Gen Richard Cody, the Army's deputy chief of staff for operations, said that US troops are given the best training and equipment possible, but casualties
"Combat is a dirty, nasty business," he said.