US intelligence officials are trying to determine whether Saddam Hussein was killed or injured by the US's pre-dawn air strikes on Baghdad on Thursday morning.
Thursday's attacks aimed to 'decapitate' the regime
Senator Pat Roberts, a Kansas Republican who chairs the Senate
intelligence committee, said on Thursday he had been told that intelligence officials do think some of the Iraqi military leadership were killed in the bombing.
Officials told the Washington Post they believe the Iraqi leader, and possibly one or both of his sons, Qusay and Uday, were inside a compound in southern Baghdad when it was bombed.
"The preponderance of the evidence is he was there when the building blew up," the newspaper quoted one official as saying.
Officials have also said they believe medical assistance was summoned to the compound soon after the attacks.
But there are conflicting reports over whether the medical assistance was called for Saddam himself.
Analysts have been scrutinising a televised message by the Iraqi president broadcast within hours of the attack, which refers to the date of the bombing and the fact that it was at dawn.
"The CIA's assessment of the tape is that it does appear to be the voice of Saddam, but there is no conclusive evidence about whether that was taped before or after the operation began," White House spokesman Ari Fleischer said.
A TV appearance suggested Saddam Hussein had survived
Later the same day, Iraqi TV showed footage of what appeared to be the president dressed in military uniform, chairing a meeting of cabinet ministers.
However there was nothing to indicate when this was filmed.
Attempt to 'decapitate'
A report from US intelligence that it had a fix on the whereabouts of Saddam Hussein prompted the cruise missile strikes, which took place at 0534 Baghdad time on Thursday.
US officials have described the attacks as an attempt to "decapitate" Saddam Hussein's government by killing senior figures.
CIA chief George Tenet reportedly told President Bush it had pinpointed the elusive Iraqi leader, presenting what one official quoted by the Washington Post described as a "target of opportunity".
But a senior official told Reuters that the raid may have been planned all along.
Several reports describe the target as a residential site where the Iraqi president and his sons may have been sleeping.
But the Washington Post quoted "a knowledgeable official" as saying the location was an underground bunker, which was part of a secure compound guarded by the Special Security Organisation, which protects the president and is commanded by his younger son Qusay.
One of Washington's stated war aims is "regime change" in Iraq.
But despite America's overwhelming military and intelligence superiority, targeting Saddam Hussein and his key lieutenants is very difficult.
Saddam Hussein is a master of self-preservation and employs a number of tactics to ensure his personal safety.
Saddam Hussein could flee to a bunker deep below any one of palaces
He has not appeared in public for more than two years and employs the 15,000 strong Special Security Organisation as his personal bodyguard.
The Iraqi president is believed to spend most of his time in discreet, ordinary houses, or his network of fortified underground bunkers.
These include underground command posts, air-raid and tank shelters and hospitals and, according to an engineer who helped build them, can resist a direct hit by a TNT bomb of 2,000 kilograms.
Spy satellites and aircraft
Remote-controlled Predator drone aircraft (above)
Electronic surveillance of communication between Iraqi officials
"Conventional weapons can hardly reach him and I don't believe the US can get rid of him that way," the unnamed source told the Reuters news agency last year.
Saddam Hussein is reputed to never sleep more than one night in the same place, apparently sometimes driving himself between locations.
It is reported that during the 1991 Gulf War, the Iraqi leader surprised a family by arriving at their Basra farmhouse and requesting a bed for the night.
He is also reputed to have spent time sleeping in a tent in the western Iraqi desert.
US officials told the Associated Press that the intelligence for Thursday's attacks came from an operation combining human sources,
electronic spying and special military operations.
The strikes suggest the US had precise information, possibly fed to the CIA by an Iraqi spy, or defector.