A Tornado GR4 was brought down
America's most senior military official has apologised for "friendly fire" incidents which killed three British soldiers.
General Richard Myers, chairman of the Joint Chiefs of Staff, told the BBC he would make it his "quest" to ensure it did not happen again.
But the commander of British armed forces in the last Gulf War says too many troops had died in such incidents this time.
Five British servicemen are believed to have been victims of "blue on blue" incidents since the war on Iraq began a week ago.
British 'friendly fire' deaths
Lance Corporal of Horse Matty Hull
Corporal Stephen John Allbutt
Trooper David Jeffrey Clarke
Flight Lt Kevin Main
Flight Lt Dave Williams
Two RAF pilots were killed last Sunday when their GR4 Tornado was shot down by an American Patriot missile near the Kuwaiti border.
Inquests into the deaths of Flight Lieutenant David Rhys Williams, 37, and Flight Lieutenant Kevin Barry Main, 35, have been opened and adjourned after their bodies were flown back to the UK.
On Friday Lance Corporal of Horse Matty Hull died when a US A-10 tankbuster aircraft fired on two armoured vehicles.
And in a third incident, two British soldiers - Corporal Stephen John Allbutt, 35, and 19-year-old Trooper David Jeffrey Clarke - were killed last Tuesday when their Challenger II tank was mistakenly fired upon by British comrades in another tank.
General Myers told BBC One's Breakfast with Frost there was "no excuse" because preventative technical procedures were in place.
He said the US felt "great sadness" about those killed by friendly fire.
The General accepted that, given the chaos of war, things happened on the battlefield but he did not accept such incidents were inevitable.
"One of my jobs has to be to ensure that we get the resources and the technical means to ensure that in the future this never, never happens again.
"And that will be my quest," he said.
General Sir Peter de la Billiere, who commanded British armed forces in the last Gulf War told the same programme friendly-fire incidents were a "reflection" of the standard of training and cooperation between the forces before the operation's outset.
"One has to ask whether the services be they British or American have been given enough time to train together," he said.
General Myers said coalition forces would have to adjust their tactics following the
suicide taxi bomb attack which killed four American soldiers near the town of
"It's just a reminder that there are some very desperate people out there and
we've got to be on our toes," he said.
He agreed the enemy was responding in a way the coalition had not "wargamed" for.
"No plan no matter how good, how brilliant, survives the first contact with the enemy," he said.
But he said at a strategic level the campaign was going according to plan.
"Certainly the tenacity, the audacity, ferociousness of what we are calling the regime death squads has had in terms of on overall strategic military impact, not much of an impact".