WASHINGTON — The United States has four broad options for military action against Osama bin Laden and Afghanistan, analysts say, each with its advantages and disadvantages:

AIRSTRIKES:

U.S. and allied aircraft could drop bombs and fire missiles at targets linked to bin Laden in Afghanistan. Navy ships in the Arabian Sea could fire Tomahawk and other cruise missiles at Afghan targets from hundreds of miles away.

PROS: Very little risk to U.S. soldiers, since war-ravaged Afghanistan's air defenses are virtually nonexistent. An airstrike also could ease political pressure for a quick military response.

CONS: Airstrikes are unlikely to hit bin Laden, who moves around frequently and is hard to track. There are also limits to how much damage bombs and missiles can do, especially if bin Laden's forces are hiding in deep mountain caves. Airstrikes in populated areas also carry a strong risk of killing or hurting civilians, which could solidify anti-American sentiment.

COMMANDOS:

A small group or groups of soldiers such as Army Rangers, Navy SEALS or Delta Force commandos could fly into Afghanistan aboard helicopters and strike quickly, killing or capturing bin Laden and/or some of his top associates.

PROS: Little risk of hurting civilians. A chance to cut off the head of bin Laden's al Qaeda terrorist network. Few U.S. soldiers at risk.

CONS: Finding bin Laden to make such a strike successful could be next to impossible, because it would require predicting his movements. A spectacular failure of a commando raid could damage morale inside and outside the U.S. military. Commandos, if captured, also could make high-profile hostages.

LIMITED INVASION:

A larger group of soldiers, perhaps 10,000 to 20,000, could invade Afghanistan, both to hunt down bin Laden and oust the Taliban regime. The force would be supported with airstrikes aimed at crushing Taliban military forces.

PROS: A better chance at having enough time and people to capture or kill the terrorism suspect. A large enough force to better defend itself. Fewer logistical problems than with a full-blown invasion.

CONS: A chance to get bogged down in a conflict with no clear ending. Long supply lines to keep soldiers fed and equipped in an arid country with little infrastructure. A larger threat of prompting internal conflict in neighboring states such as Pakistan, which has more than two million Afghan refugees and a large number of supporters of the Taliban and bin Laden. Instability in Pakistan is particularly troubling because the country has nuclear weapons.

LARGE INVASION:

After massive airstrikes, a force of hundreds of thousands of ground troops could invade Afghanistan, hunting down bin Laden and his supporters and ousting the Taliban. Unlike the invasion of Iraq during the Gulf War, the invasion would rely more on infantry than on tanks and other vehicles, since rugged Afghanistan has few roads.

PROS: Such an overwhelming force could make it nearly impossible for the Taliban to keep control of its present territory. The large number of troops also would make it easier to search out bin Laden's network and destroy whatever remains of it in Afghanistan.

CONS: Such a large buildup of troops would be impossible to do in secret; bin Laden probably would have time to flee Afghanistan. Supplying such a large number of troops in such remote areas would be challenging. As Russia discovered, it would be easy to become snared in a long-running, guerrilla war. Large-scale fighting also would worsen refugee problems in the area, and could create conflict within Pakistan.