By Mark Trevelyan, Security Correspondent
LONDON (Reuters) - Abandoning his Kalashnikov and dyeing his beard from grey to black, Osama bin Laden presents a new image to the world in a video that makes no specific threats but may be a signal for new al Qaeda attacks.
In a half-hour address released four days before the sixth anniversary of the September 11 attacks on the United States, bin Laden lurched between history lesson and sermon, urging Americans to ditch capitalist democracy and embrace Islam if they want to end the war in Iraq.
Despite its lack of specific warnings, several security analysts said bin Laden's first video for nearly three years could be a signal to his followers to launch new strikes.
"Osama's call to the Americans to convert to Islam is indicative of an al Qaeda attack on U.S. targets. Before the Prophet (Mohammad) attacked his enemies he urged his opponents to embrace Islam," Rohan Gunaratna, a leading authority on militant Islamism, told Reuters.
"Osama is presenting Koranic injunctions before planning to attack."
Abdel Bari Atwan, London-based editor-in-chief of the Arabic newspaper al-Quds, said: "Maybe this is a warning that an attack could happen soon ... This is a sort of rallying video. Maybe there is a message to his followers: go ahead and do what you want to do."
Atwan, who has interviewed bin Laden, said the video marked a significant shift in the al Qaeda leader's style and image.
By trimming and dyeing his beard and ditching his military camouflage jacket for Arabic robes, bin Laden was trying to portray himself as a new, mature figure -- the spiritual leader of al Qaeda, Atwan said.