It started as a low, largely unnoticed rumble of accusations in some Washington circles, but when suicide bombers fatally struck Western targets in Saudi Arabia last week, the official grumblings began to pick up volume and pitch.
More than a year ago, Defense Secretary Donald Rumsfeld complained that Iran — a member of Washington's "axis of evil" and an officially condemned "supporter of terrorists" — was not doing enough to crack down on al Qaeda operatives fleeing from neighboring Afghanistan.
"It certainly would be helpful if they were more cooperative, and they have not been, particularly," Rumsfeld told reporters in Washington on April 2, 2002, in a second straight day of accusations against the Islamic Republic of Iran.
But in the months that followed, international attention shifted from Tehran's alleged links to al Qaeda to the hunt for evidence of Saddam Hussein's touted ties with the terrorist network as the Bush administration sought to bolster its case for a war against Iraq.
Days after President Bush declared that the military phase of the battle to topple Saddam's regime was "one victory in a war on terror" however, terrorists struck again. This time, it was a spate of suicide attacks in the Saudi capital of Riyadh, which claimed 34 lives, including eight Americans and nine attackers.
A reconfigured al Qaeda, revamped under the pressure of the U.S. war on terror, was quickly identified as the mastermind and perpetrator of the crime.
And slowly, the accusations of the Iranian government's links with al Qaeda began to mount as the terror alert in the United States was raised to orange or "high" following an FBI warning about imminent attacks.
"There's no question, but that there have been and are today, senior al Qaeda leaders in Iran, and they are busy," Rumsfeld told reporters on Wednesday.
But if the accusations were strong on frequency, they were noticeably weak on details, with senior U.S. officials declining to go on record with concrete proof of the Iranian government's supposed support for the shadowy terrorist network.
Former Colonel Becomes 'Military Chief'
But although U.S. officials have declined to go on record with concrete evidence of the Iranian government's complicity in al Qaeda's recent operations, terror experts and intelligence sources have attempted to fill in the gaps in the latest accusations.
And at the heart of the claims, it slowly became clear, was a handsome young former colonel in the Egyptian Army, Saif Al-Adel, who experts claim has risen from the ranks of one of Osama bin Laden's personal guards to al Qaeda's new military chief and the third-most powerful man in the terrorist network's ranks. He is on the U.S. list of 22 most-wanted terrorists.
"Saif Al-Adel is the newly appointed military chief of al Qaeda who took over as military chief when Khalid Sheikh Mohammed was captured [in Pakistan earlier this year]," said Rohan Gunaratna, a former investigator at the U.N. Terrorism Prevention Branch, and author of Inside Al Qaeda: Global Network of Terror.
"He is operating near the Afghan-Iran border and he is responsible for the attacks in Saudi Arabia," he said.
U.S. intelligence officials and some terror experts say Saif Al-Adel has been living in the eastern border regions of Iran under the protection of the Iranian Revolutionary Guards, or Pasdaran, an elite military force under the direct control of the Islamic republic's supreme leader Ayatollah Ali Khamenei.