ISLAMABAD, Pakistan -- If Osama bin Laden is directing plans for an attack on the United States -- as Washington intelligence officials suspect -- his instructions are likely coming out of the craggy mountains between Afghanistan and Pakistan on the back of a donkey or under the shawl of an unassuming-looking villager.
After the arrests of several top lieutenants, bin Laden and his right-hand man, Egyptian Ayman al-Zawahri, have learned their lessons well, Pakistani intelligence officials and international terrorism experts say. They don't use satellite or cellular phones, don't trust anyone outside their innermost circle and never come up for air.
From hand to hand
Messages from the men likely pass through the hands of many couriers, most of whom have no idea where they originated, before they are turned into e-mails or conveyed by phone calls to other militants.
"If bin Laden wants to convey something, he gives a letter to someone in his circle, who takes it a certain distance and then hands it to someone else, and then someone else until it reaches its final destination. Nobody knows who the letter is from except the first person who is one of bin Laden's most trusted men," said a senior Pakistani intelligence official who has been in on his nation's most sensitive counterterror operations.
The Bush administration believes plans for a terror attack are being directed at the most senior levels of the al-Qaida leadership, including bin Laden, a U.S. intelligence official told The Associated Press in July.
How much input the top men have is open to question, but a Pakistani government official told the AP that several captured al-Qaida men have told authorities they received instructions from bin Laden.
"Probably he is alive, and some al-Qaida suspects captured in Pakistan have talked about receiving verbal messages from him through different channels," he said of bin Laden.
The American and Pakistani officials spoke on condition of anonymity.
There has been no firm intelligence on bin Laden and al-Zawahri's whereabouts since they slipped away during a U.S.-Afghan assault on their mountain hideouts in Tora Bora in late 2001, but they are believed to be hiding in the mountainous no man's land between Pakistan and Afghanistan, protected by deeply conservative tribesmen who share their beliefs.
With the exception of about a half-dozen audio taped messages that the CIA has authenticated as being his voice, there has been virtually no sign of bin Laden since shortly after the Sept. 11, 2001, attacks. That silence has lent him almost a mythic quality, especially among his followers, but officials say he is still very real, and very dangerous.
Lead from No. 3 man
The Pakistani intelligence official said one of the best leads came with the arrest of al-Qaida's No. 3 man, Khalid Shaikh Mohammed, who had a letter on him that he told interrogators he got directly from bin Laden, and which experts authenticated as being in bin Laden's handwriting.
The letter was apparently personal and destined for several of bin Laden's relatives in Iran, the official said. He would give no further details.
"Khalid Shaikh Mohammed said he got the letter directly from bin Laden and was supposed to give it to someone else and it would eventually go to Iran," the official said. He said the letter proves bin Laden was alive as recently as early 2003. Mohammed was arrested in Pakistan on March 1, 2003, and is now in U.S. custody.
Several top al-Qaida fugitives arrested in Pakistan have allegedly been tracked using satellite intercepts, including Abu Zubaydah and Ramzi Binalshibh. A tribal elder accused of sheltering foreign militants was killed in a bombing in Waziristan on June 18, hours after he used a satellite phone to call media to denounce the government.
The importance of discretion has become even more apparent in recent weeks following the July 13 arrest of an alleged al-Qaida computer whiz named Mohammed Naeem Noor Khan. Intelligence gleaned from Khan and his computer has led to counterterrorism operations in Pakistan, Britain and the United Arab Emirates, and dozens of suspects have been arrested.
Khan's computer contained a trove of information, including coded e-mails to other operatives. He is said to have cooperated with authorities and sent e-mails while in custody to militants so that authorities could arrest them.
Armed with electronic intelligence, raids in Pakistan have netted Ahmed Khalfan Ghailani, a Tanzanian with a $25 million U.S. bounty on his head, and at least 19 other suspects.
Authorities in Dubai detained Qari Saifullah Akhtar, a Pakistani with close links to bin Laden who ran an Afghan training camp through which some 3,500 militants passed. In Britain, a dozen suspects have been picked up, including a senior al-Qaida operative identified as Abu Eisa al-Hindi or Abu Musa al-Hindi who was reportedly involved in surveillance on financial institutions in Washington and New York.
"Terrorists, like the rest of us, are finding out that they cannot live without the Internet. It is very difficult to keep in touch with a lot of people over large distances without it," said Paul Wilkinson, chairman of the Centre for the Study of Terrorism and Political Violence at the University of St. Andrews in Scotland.
He said al-Qaida operatives have used encrypted e-mails and other techniques, like hiding messages inside photographs, to conceal communications. But they can't always hide, and when authorities get diskettes or hard drives, they can deal terror groups a major blow. "The technology that al-Qaida has used so effectively can also be its Achilles heel," he said.
Pakistani authorities say bin Laden and al-Zawahri have shielded themselves, staying clear of the chatter between lower ranking operatives. Bin Laden is seen mostly as a financial backer and religious inspiration to his fighters, making regular communication unnecessary.
"Whenever we get hold of high profile al-Qaida activists there is a great deal of euphoria and excitement, and it leads to a lot of optimism ... that it will lead us to the eventual prize -- the apprehension of Osama and al-Zawahri," said Interior Minister Faisal Saleh Hayyat. "But we have to be very cautious. This network ... remains a potent threat to Pakistan, and to civilized humanity."
The Pakistani intelligence official acknowledged that the lack of solid intelligence has been frustrating.
"You keep waving your sword in the air and you hope a bird will come along and you will hit it," he said. "It's a matter of luck."
Associated Press Writer Munir Ahmad in Islamabad contributed to this report.