Iraq's Ho Chi Minh Trail

BAGHDAD, Iraq — Some American officers call him 'Z.' In the military's classified signal traffic, he is 'AMZ.' By any name, American forces in Iraq have found in Abu Musab al-Zarqawi a mesmerizing target.

At Husayba, scene of recent fighting, an Iraqi girl peering from a gate as an American tank patrols.

If they could capture this Jordanian-born militant, anointed by Osama bin Laden as Al Qaeda's chief in Iraq, American commanders are hoping, they could strike a compelling, perhaps decisive, blow against one crucial component of the Iraqi insurgency - the Islamic militant groups that draw zealots from across the Arab Middle East to carry out suicide bombings, beheadings and other atrocities.

The capture of Saddam Hussein in 2003 dealt the insurrection no such mortal blow, and American commanders know Mr. Zarqawi's capture or death might not either. 'It's not about one guy,' a senior officer said Friday. 'It's more about the network of cells he has across the country. That's where we're applying the pressure.'"