-- To date there has been no official estimate of the number of civilians killed by US-led forces who launched the war on March 20. Officials at the war command headquarters in Qatar have repeatedly blamed Saddam Hussein for the casualties, claiming he placed troops and materiel in civilian zones.

-- On March 26, 15 people were killed when a bomb landed on a housing complex. Iraqi officials blamed US forces, who said they were looking into the incident.

-- On March 28, 30 people were killed when a Baghdad market was bombed. Here again the Iraqi leadership accused the US military, who said the incident was under investigation.

-- Seven women and children were killed in the southern city of Najaf on March 31, when US troops opened fire on a civilian vehicle that failed to stop at a military checkpoint. A Washington Post reporter on the scene said the US troops did not fire a warning shot.

-- The United States has yet to present a clear explanation of what exactly happened when shots were fired at the convoy in which the Russian ambassador to Iraq was fleeing Baghdad on April 6.

-- US military strikes killed three journalists in Baghdad on April 8. A cameraman from the Reuters news agency and another from Spanish television station Telecinco were killed after a US tank fired on Baghdad's Palestine hotel, where most foreign journalists are based. A correspondent for Arabic television network Al-Jazeera was also killed when a US missile crashed into the station's offices in the Iraqi capital the same day. Brooks said US forces "will look into the circumstances" of the incident.

-- Another shooting at a checkpoint occurred on April 11 in the southern town of Nasiriyah, resulting in the deaths of two children.

-- On April 15 and 16, US Marines fired upon what the Central Command described as a "hostile" crowd in the northern city of Mosul. Witnesses say 19 civilians were killed. A US military spokesman put the April 15 death toll at seven and said an undetermined number of people were killed the next day. "The full scope of that is not ever completely well-known. Some move away with wounds and we don't ever know about that," Brigadier General Vincent Brooks said at the US command center in As-Saliyah, Qatar.

-- Several incidents of friendly fire, notably with US troops firing on allied British forces, are also being investigated.

-- The weapons of mass destruction cited as the grounds for launching the war have yet to be found. US officials remain convinced the banned weapons are hidden somewhere and will eventually be uncovered.

-- The whereabouts of Saddam Hussein remain a mystery, and no one appears to know whether he is alive or dead. US military leaders say they have been unable to determine whether Saddam was in a Baghdad complex bombed on April 7. Fourteen people were killed in the bombing, according to witnesses.

-- It also remains unclear whether the man known as "Chemical Ali" was killed in an air raid by coalition forces in the southern city of Basra. A notorious aide to Saddam, Ali Hassan al-Majid is blamed for gassing to death thousands of Kurds in northern Iraq.

-- US military officials have yet to explain why a Saddam government stalwart, information minister Mohammed Said al-Sahhaf, whose whereabouts are also unknown, is not on a list of 55 wanted Iraqis.

SPACE.WIRE