Precision airstrikes by US and British forces have weakened the Taliban's air defenses and opened up the skies over Afghanistan, setting the stage for far more difficult ground operations in the war on terrorism.
In contrast to this first volley of missiles and bombs, the campaign to come will last much longer, be far more complicated, and carry much greater risk for America - both militarily and diplomatically.
"The hard part ... is ahead," said Sen. John McCain (R) of Arizona yesterday, echoing the sentiment of US and allied defense officials. Senator McCain, a Navy veteran who sits on the Senate Armed Services Committee, says the next phase would likely include the "insertion and extraction" of small numbers of ground troops on search-and-destroy missions against Osama bin Laden's organization.
Defense Secretary Donald Rumsfeld stressed that the airstrikes are only the beginning of the effort to expel from Afghanistan both the terrorists and the Taliban leaders who back them. Taken alone, he said, the strikes are unlikely to "rock the Taliban back on their heels," given the absence of high-value targets in a nation already pounded into "rubble" during earlier fighting with the former Soviet Union.
"The cruise missiles and bombers are not going to solve this problem. We know that," he said at a Pentagon briefing Monday. "What they can do is to contribute by adding pressure, making life more difficult, raising the cost for the terrorists and those that are supporting [them]."
In recent days, dozens of targets - including Taliban-controlled early-warning radar systems, airfields, and aircraft, as well as command centers and troop concentrations - have been hit.
Training camps and troops of the Al Qaeda terrorist organization of Mr. bin Laden have also been targets, according to the Pentagon.
Daytime strikes on Afghanistan Tuesday suggested US military commanders are at least somewhat confident in having dismantled Taliban air defenses, opening the way for round-the-clock US bombing of mobile targets such as troops and tanks, experts say.
Specifically, the aerial bombing is intended to clear the way for two types of high-risk ground offensives: an advance on the Taliban regime by internal opposition forces such as the Northern Alliance, and small-scale US and allied commando operations aimed at destroying bin Laden's Al Qaeda network and other terrorist groups in Afghanistan.
Some experts predict that teams of elite US Special Operations Forces could begin short-term actions within days.
Their goals could range from destroying military and communications targets that are hard to hit from the air, to investigating terrorist training camps, to seeking out the terrorists themselves, says Chris Hellman, a senior analyst at the Center for Defense Information, an independent defense think tank in Washington.
Yet the success of such operations will depend heavily on the quality of intelligence, which is still lacking, experts say.
"We ran into the exact same problem in Somalia, which is a dearth of good intelligence," says Mr. Hellman. "We will have to rely, to a large extent,... on paid informants, [and] a lot of the time they totally miss the boat."
US officials and experts stress that they do not expect any larger-scale ground invasion involving hundreds or thousands of US troops. Such an occupation would be "the height of foolishness," says McCain.
US forces, though, could become more directly involved in efforts by the Northern Alliance and other internal anti-Taliban groups to overthrow the Taliban regime. Secretary Rumsfeld has not ruled out providing air cover and other assistance to Northern Alliance forces, and experts say limited numbers of American troops could serve as combat advisers to the Northern Alliance as it attempts to advance on the Taliban from its base north of Kabul.
The United States continues to encourage the Northern Alliance and other anti-Taliban groups, seeking to build up pressure on the Taliban regime "so that it eventually creates a situation internally where it disintegrates and falls apart," in the words of Rumsfeld.
Yet Washington has so far been careful to avoid the appearance of a partnership with the Northern Alliance or other specific opposition groups, because that would carry major strategic as well as political risks, experts say.
Above all, the Bush administration seeks to avoid military entanglement in Afghanistan's civil war, or taking sides with the Northern Alliance in a way that could unite and provoke the deeply factional Afghan militias against it.
There are also worries that the first civilian casualties of the US airstrikes - including the deaths of four United Nations land-mine-removal workers near Kabul, reported Tuesday - could generate fresh popular support for the Taliban, especially if the civilian losses increase.
Protests of thousands of people against the US strikes erupted again Tuesday among Muslim groups in Pakistan and other nations, leading to new concerns about the solidity of the US-built coalition against terrorism.
Since the strikes began on Sunday, televised statements by bin Laden and the Taliban have attempted to portray the war on terrorism as a battle between Western infidels and the Islamic faithful - a depiction that US officials vigorously dispute.