"It seemed to be a reminder that 'I am still here, and I'm still actively directing my cause, and do not forget the role I am playing in this conflict,' " Post said. "He clearly is very PR-minded. There has been a consistency over the years. He is acutely aware of his image."
Although bin Laden has consistently charged that the United States oppresses Muslims, the examples he cites have changed over the years.
In 1996, when he issued his declaration of war against American interests, the primary offense he mentioned was the presence of U.S. troops in Saudi Arabia. They had used military bases in the kingdom during the 1991 Persian Gulf War and remained there afterward at the request of the Saudi royal family. Having "Crusader warriors" near the holy shrines of Mecca and Medina was a grave insult to all Muslims, bin Laden and other conservative members of the faith complained.
U.S. troops largely withdrew from the kingdom by September 2003, but their departure did not end al Qaeda operations in the region. Instead, sympathizers of the group have since increased their attacks on interests of the United States and others they consider to be enemies in the kingdom.
Bin Laden has continued to list U.S. support of the Saudi royal family -- which he regards as corrupt and beholden to outside interests -- as one of his biggest grievances. But he has also displayed a politician's instinct by tapping into two other issues that have inflamed public opinion in the Middle East more recently: the war in Iraq and the Israeli-Palestinian conflict.
In his videotaped speech last month, bin Laden said he drew the inspiration for the Sept. 11 attacks from his memories of the Israeli invasion of Lebanon in 1982 and the bombardment that began the following year of targets in that country by a U.S. battleship. Another factor was the U.S.-led embargo of Iraq after the Gulf War, which he claimed led to "the greatest mass slaughter of children mankind has ever known."
"With these images and their like as their background, the events of September 11th came as a reply to those great wrongs," he said. "It confirmed to me that oppression and the intentional killing of women and children is a deliberate American policy."
In a report published last week, the Congressional Research Service said that al Qaeda "has displayed a pragmatic willingness to adapt its statements to changing circumstances while remaining a messianic commitment to its ideological agenda." Bin Laden, it added, "continues to see himself and his followers as the vanguard of an international Islamic movement."
A European intelligence official said bin Laden's strategy has always been to cast himself as a leader of a larger cause and to show that Muslims can successfully stand up to the United States.
"He's trying to pose as a politician," said the official, who spoke on condition of anonymity. "If you look back at his old speeches and videotapes, he always sees himself as being on an eye level with the American president. He's trying to show that he's a force to be reckoned with."
While bin Laden has made a name for himself as a sworn enemy of the United States, he also presents himself as a believer in the power of democracy.
By addressing the American people directly, the al Qaeda leader was serving notice that he held them accountable for electing their leaders and, indirectly, for shaping their country's policy toward the Islamic world, said Maha Azzam, an al Qaeda expert and fellow at the Royal Institute of International Affairs in London.
Azzam noted that bin Laden took a similar approach in an audiotape he released in April warning European countries that they had three months to withdraw their support of the U.S. occupation of Iraq or face more terrorist attacks like the bombings on March 11 of four commuter trains in Madrid, in which 190 people were killed and more than 1,800 were injured.
"My reading is that there is a belief on the part of bin Laden as well as other Islamists that democracy works and that voters in the U.S. and Europe can influence foreign policy decisions," Azzam said. "On the one hand, they attack the West. On the other hand, there is recognition that in a democracy, people can hold its leaders accountable. He believes that democracy is a system that can deliver on behalf of its people."
In his last videotape, for instance, bin Laden repeatedly mocked President Bush as an ineffective leader who had failed to serve the interests of the American people.
He made fun of Bush for reading "My Pet Goat" to Florida schoolchildren while hijackers flew planes into the World Trade Center. He said that al Qaeda planners assumed they would have at most 20 minutes to carry out the attacks but that it took the Bush administration almost a full hour to respond.
He also compared the Bush family to the royal House of Saud, saying that both ruling clans were "characterized by pride, arrogance, greed and misappropriation of wealth." The war in Iraq, he said, was fought to benefit the U.S. oil industry and companies such as Halliburton but had left the U.S. economy in shambles and the federal government with a huge budget deficit.
The point, bin Laden added, was not that the Democratic presidential candidate, Sen. John F. Kerry, would be a better choice. Rather, he said, it was that the American people were responsible for the actions of their leaders and that they would face the consequences for U.S. actions in the Middle East.
Toward the end of his speech, he urged Americans "to reflect on the last wills and testaments of the thousands who left you on the 11th as they gestured in despair," a reference to what he claimed the victims of the attacks were thinking as they died.
"It is as if they were telling you, the people of America, 'Hold to account those who have caused us to be killed, and happy is he who learns from others' mistakes,' " bin Laden said.
Researcher Julie Tate in Washington contributed to this report.