Tuesday's tape, thought to be by bin Laden, urges Muslims to use guerrilla tactics against US troops.
Do not expect to see Islamic warriors mounted on camels, turbans flowing in the wind, charging across the Arabian desert to defend Baghdad.
More likely, say Western military analysts, a slow, stealthy infiltration of extremist groups could wreak havoc on US, British, and allied armies during and after a coalition invasion of Iraq.
Thousands, perhaps tens of thousands, of jihadis - holy warriors - will view US and British forces in Iraq as prime targets, say these analysts. They say coalition forces could wind up fighting two campaigns: one to disarm Saddam Hussein and the other to maintain security afterward - putting down skirmishes between tribal factions while defending against possible terrorist attacks (see story, page 1).
In a new audiocassette released on Tuesday, a voice believed by US officials to be that of Al Qaeda chief Osama bin Laden calls on Muslims around the Arab world to take up just such stealthy, guerrilla tactics against "infidels" on Arabian sands.
"True Muslims should act, incite, and mobilize...." the tape said. "We advise about the importance of drawing the enemy into long, close, and exhausting fighting, taking advantage of camouflaged positions in plains, farms, mountains, and cities."
Western military analysts warn that while Iraq is today a mostly "secular" Islamic regime run by Mr. Hussein's ruling Baath Party, Western armies are likely to act as magnet that would draw Al Qaeda across porous borders into Iraq.
"There is a real possibility that an occupation of this nature will suck in all sorts of jihadis from all over," says Charles Heyman, editor of Jane's World Armies in London. "A Western occupation almost certainly invites them in from Saudi Arabia and other countries where they are currently ensconced."
Abu Omar, an Iraqi businessman here, says that he was pleased to see Mr. bin Laden, a personal hero, taking an interest in Iraq. But he said that he also wanted to see Hussein removed from power, albeit not with the help of the US military.