WASHINGTON -- Any U.S. forces entering Afghanistan would face a hostile land and fighters with a history of vanquishing some of the world's finest armies.
The fighters of the Taliban and Osama bin Laden are not heavily armed but they are battle-hardened and dispersed in a mountainous country filled with places to hide.
These factors make assaults by small units of U.S. special forces, combined with precision strikes from aircraft or ship-launched cruise missiles, the most likely means of attack, military analysts say. The massive bombing campaigns and fast-paced tank blitzes of the Gulf War won't work in the environment of Afghanistan.
Defense Secretary Donald H. Rumsfeld knows the challenges.
"Several countries have exhausted themselves pounding that country," he said, referring to Britain, which attempted to conquer Afghanistan in the 19th century, and the former Soviet Union, whose brutal 1979-89 war there against Islamic rebels helped bring about the superpower's collapse.
"What we'll have to do is exactly what I said: Use the full spectrum of our capabilities."
It's unclear precisely whom the United States would be fighting. Bin Laden's forces and training camps operate somewhat separately from the military forces of Afghanistan's rulers, the Taliban. Attacking bin Laden may mean fighting the Taliban, which refers to him as a guest.
Allied help needed
To launch a sustained campaign, the United States needs help from allied nations in the region, said Jonathan Pollack, director for strategic research at the Naval War College. Those nations can provide friendly airspace, a base of operations for U.S. troops and aircraft, and intelligence information, all vital to any U.S. effort, Pollack said.
Pakistan has good, up-to-date information on events in Afghanistan and could provide air corridors across its territory, allowing carrier-based aircraft from the Arabian Sea to hit targets in Afghanistan.
Another key ally would be Russia, Pollack said, because they know the territory from a decade of war. Continuing Afghani resistance, supported by the United States, eventually caused the Soviets to leave in 1989.
U.S. troops may also have an ally in the forces of the Northern Alliance, the chief opponent to the Taliban in Afghanistan's ongoing civil war. The group holds some territory in the country's northeastern reaches, but the general leading the alliance was assassinated just before the Sept. 11 terrorist attacks in New York and Washington.
Some of bin Laden's people, brought in from Muslim countries throughout the region, fight alongside the Taliban in the civil war, usually as a form of training. They later return to their home countries and join terrorist networks there.
Bin Laden's al-Qaida organization (pronounced ahl-KAY'-duh) is believed to have several hundred fighters in-country. Primary targets for a U.S. campaign could be al-Qaida's training camps, located in several provinces in eastern Afghanistan. Some are hidden in natural caverns that have been expanded into underground networks, concealed from satellites and aircraft.
50,000 Taliban troops
The Taliban, meanwhile, has about 50,000 troops and foreign volunteers, according to various estimates. Most are armed with AK assault rifles and some heavier weapons, including mortars and rocket-propelled grenades, according to reports from Jane's Information Group, an independent military research and publishing firm. Most of the Taliban's forces are arrayed to oppose the Northern Alliance on fronts just north of the national capital, Kabul, and near Konduz to the northwest.
A typical Taliban military unit is eight to 10 armed men in the back of a pickup truck -- what the U.S. military calls "light motorized infantry." Organization is thin, and attacks are usually made by forces thrown together. A favorite Taliban tactic is to bribe opposing commanders to stop fighting, according to Jane's and other analysts.
The Taliban has about 650 tanks and armored vehicles, mostly Soviet-era scout cars and armored personnel carriers, according to Jane's. Its air force consists of a few old Soviet fighters, used almost exclusively as bombers. It has a few dozen transport planes that can move larger forces around quickly.
Air defense differences
Afghanistan does not have the Soviet-built air defense and command-and-control networks that the United States faced in Serbia and Iraq -- making the men and women flying U.S. aircraft less likely to be shot down, but depriving bombers the ability to quickly disable centralized communications networks.
Some U.S. Stinger anti-aircraft missiles, supplied by the CIA to rebels fighting the Soviets, probably remain in the country. It's unclear who has them or how many still work.
The Taliban isn't believed to have any working ballistic missiles, like the Scud of the Gulf War.
Ali Jalali, a former Afghani mujahideen rebel turned chief of the Farsi service of Voice of America, doesn't think the U.S. forces would face such a danger than earlier armies.
"The British army, the Soviet army -- they faced a nation," he said. "(U.S. forces) are not there to occupy the country. They are trying to root out terrorism."