On Dec. 1, 2001, American B-52 bombers launched a bombing campaign on Al Qaeda positions in the rugged Tora Bora mountains, one of the biggest campaigns in the US war effort here to capture or kill Osama bin Laden and his terrorist cohorts.
Just a year later, the B-52s hit the skies again in western province of Herat - this time because of fighting between rival warlords who are part of the new government.
Though combat operations to root out Al Qaeda and Taliban fugitives continue across Afghanistan, diplomats and analysts say the conflict here - and America's role in it - has changed dramatically.
"America has lost a year simply preserving the status quo here," says Ahmed Rashid, an author of several books on Afghanistan and Central Asia. "Finally now they seem to be moving forward."
Yet establishing stability in this war-devastated nation, or effectively supporting nation-building policies the Bush administration once shied away from, may prove as tricky as toppling the hard-line Taliban looked simple.
The biggest challenge to security in Afghanistan these days is less terrorists in hideouts and more the regional warlords who want a stake in future power - and are ready to kill for it.
The fighting last weekend near a key western air base, which left about a dozen dead, was only the latest burst of violence between Herat governor Ismail Khan, an ethnic Tajik, and his Pashtun rival Amanullah Khan. It stopped only after US warplanes bombed both sides of the front line.
"Bombs exploded on Ismail Khan's side and others exploded on our side," Amanullah Khan told the Associated Press. "We think the Americans were dropping bombs to end the fighting."
US military spokesman Col. Roger Kings insists that American B-52s struck the front lines only because a Green Beret patrol in the area got caught in the crossfire and called in air assistance. "We don't get involved with green on green [allies fighting one another] unless our soldiers are at risk," he says.
But American diplomats say privately that it works very much to their favor that the warlords believe the warplanes were sent in to quell the fighting.
US officials hope this misunderstanding will give other armed groups pause to reconsider similar violence in the future.
The spasm of ferocity in Herat was hardly unique. America's embassy here has had to respond more directly to fighting in Afghanistan's regional fiefdoms. Last June, US Envoy Robert Finn halted further assistance to northern areas of Afghanistan where Uzbek strongman Rashid Dostum continues to battle his adversary Mohammed Atta, an ethnic Tajik.
And anti-Taliban warlords in southern Afghanistan such as Pacha Khan Zadran and Gul Agha Sherzai, once allies of the US war on terror, fell from favor once they resorted to aggression to maintain their grips on power or to settle local scores.
Even Defense Minister and Vice President Mohammad Fahim, whose unruly Panjshiri troops have at times wreaked havoc on rival ethnic groups in Kabul and who is suspected of stashing arms north of Kabul, has come under intense pressure to play along with the new nation-building efforts at work.
Key to long-term security will be following through on President Hamid Karzai's plan, outlined last week at a Bonn conference. The plan would establish a 70,000-strong national army representing Afghanistan's mosaic of ethnic groups and supporting efforts to bring much-needed revenue collected outside the capital into federal coffers.
Diplomats close to negotiations over who will make up the new army - and which warlords will be allowed to play a role in it - describe rampant attempts to cheat the system.
"There is amazing inflation in the numbers of officers and staff that each claims to control," said one European diplomat.
In a preemptive bid to make the process go more smoothly, the Pentagon last month announced it would be sending US troops to outposts around Afghanistan. US diplomats have been posted to major cities across the country, and American soldiers in Kabul are training troops in the fledgling Afghan National Army.
And while combat missions to hunt terrorists will continue, US military officials say the balance of their work here will tilt toward increasing military-led humanitarian efforts.
"For the last year, the Americans never strategized about nation-building," says Mr. Rashid. "Now they are being forced to do it on the hop."