ISLAMABAD, Pakistan -- For a man reputedly at the forefront of Al Qaeda's global terror operations -- with one finger in plots to target America and another in attempts to assassinate Pakistan's president -- Hamza Rabia kept a remarkably low profile.
The Egyptian wasn't on the FBI's list of the world's 15 most wanted terrorists, nor had he made Pakistan's most wanted list. In fact, there had been little public mention of Rabia before he was apparently killed last week in an explosion at his tribal hideout.
US officials haven't confirmed the death, despite claims by Pakistan's president, General Pervez Musharraf, that he is ''200 percent" sure Rabia died. Yet officials in Islamabad and Washington have been quick to agree that Rabia's demise would be a major blow to Osama bin Laden's terror network, saying he ranked in the top five of its hierarchy.
US national security adviser Stephen Hadley described Rabia as Al Qaeda's head of operations, adding in an interview with ''Fox News Sunday" that ''we believe he was involved in planning for attacks against the United States."
How could a man so powerful, in such a critical position, escape attention for so long?
Skeptics are demanding more information about Rabia's role in alleged plots, and pointing to what they see as a troubling trend in Pakistan and the United States of hyping counterterrorism successes that may not be as big as claimed.
''He may be a serious planner that has been lurking in the shadows, but I would like to see more evidence of his terrorist credentials before saying he's a particular number in the hierarchy. I think these are relatively low-level operators," said Magnus Ranstorp, a terrorism expert at the Swedish National Defense College, referring to Rabia and his associate, Abu Faraj al-Libbi, who was captured in Pakistan in May.
Pakistan says both men had a hand in twin attempts to assassinate Musharraf in December 2003.
Information Minister Sheikh Rashid Ahmed told the Associated Press that Rabia was Al Qaeda's No. 5 leader. Two US counterterrorism officials, who spoke on condition of anonymity because of the information's sensitivity, said he was possibly as high as No. 3, just below bin Laden and his lieutenant, Ayman al-Zawahri.
But Paul Wilkinson, chairman of the Center for the Study of Terrorism and Political Violence at the University of St. Andrews in Scotland, said Rabia appears to have been more of a ground commander, not a key international terror mastermind.
''There have been so many people suggested as the No. 3 in Al Qaeda that I would not go along with that, though he is clearly a valued member of the hierarchy," he said. ''We can't really say that he will be a major loss in terms of planning because he didn't have a profile in that area."
Almost nothing of Rabia's background is known publicly.
Three Pakistani intelligence agents told AP yesterday that he came to the country from Afghanistan in 2003, and that he is believed to have largely remained in the tribal regions of North and South Waziristan. They spoke on condition of anonymity because of the secretive nature of their work.
Rabia is said to be Egyptian, but Pakistani and American officials have not said where in Egypt he is from, nor whether he was wanted by authorities there. One Pakistani intelligence official said he is believed to have been in his 40s.
While Hadley said Rabia was linked to plots against the United States, US and Pakistani officials haven't given specifics and it's not clear how long Rabia had been an Al Qaeda member.
Even Rabia's apparent death is murky.
Tribesmen recovered the remains of what appear to be a US Hellfire missile from the wreckage of the house where Rabia reportedly was killed Thursday near Miran Shah, in the tribal North Waziristan region bordering Afghanistan. The metal pieces bore the designator ''AGM-114," the words ''guided missile" and the initials ''US."
But Pakistani leaders insisted yesterday that Rabia and three others died in an accidental explosion while making a bomb. Washington has declined to confirm any involvement in the attack, though an NBC television report, citing unidentified officials, said a US drone launched the strike. It wasn't even clear whether Rabia's body has been recovered.
Pakistani officials wouldn't say whether they have Rabia's body, saying only that DNA tests and communication intercepts confirm he is dead. Karachi-based Dawn newspaper, citing officials it did not identify, reported his body had been retrieved by associates from outside Pakistan.
Ranstorp said he feared the story was being touted in Washington and Islamabad for political reasons. The two countries are allies in the war on terrorism, both with a stake in showing their uneasy partnership is bearing fruit.
''I think it is a legitimate question to ask whether this guy was really such a big fish," he said. ''There has been an unending cavalcade of faces that roll by of people who supposedly represent a clear and present danger to [US] national security, and all this deflects attention away from the incredible failure of the war on terrorism to capture bin Laden or al-Zawahri."