The Taliban has taunted the United States with the prospect of "utter defeat" in Afghanistan, marking the 11th anniversary of the 9/11 attacks that saw US troops invade to bring down the militia's repressive regime.
The anniversary itself was muted in Afghanistan, where US and NATO troops organised only small ceremonies to commemorate the deaths of nearly 3000 people in the worst terror strike on US soil.
Soldiers sang the US national anthem and said prayers on behalf of the victims, said an AFP photographer who attended one of the commemorations.
On the eve of the anniversary, a rocket fired by insurgents on the largest US base in Afghanistan destroyed a helicopter, killing three Afghan intelligence agents, officials said.
On the day itself, a suicide bomber killed a local Afghan police commander and four civilians in a shop in a remote town near the border with Turkmenistan.
There was no immediate claim of responsibility for the suicide attack, but in a statement posted online ahead of the anniversary, the Taliban said the United States "is facing utter defeat in Afghanistan militarily, politically, economically and in all other facets".
The militia said the war had "no legal or ethical" basis and that Afghans had "no hand" in what happened on September 11, 2001, and that despite the billions spent on the conflict "no American is safe in any society today".
The United States led international military action to bring down the Taliban regime in October 2001 because it refused to give up Al-Qaeda boss Osama bin Laden, who ultimately escaped into Pakistan, where he was shot dead by US forces in May 2011.
A report from a British think-tank suggested this week that the Taliban are open to a ceasefire and a political agreement that could lead to a US military presence in Afghanistan until 2024.
The report from the Royal United Services Institute claims to reveal an emerging, pragmatic consensus among the Taliban leadership, who are willing to take part in peace negotiations in exchange for political leverage after 2014.
The report said that so far no Taliban leader has endorsed a possible ceasefire in public.
On Tuesday, a Taliban spokesman flatly denied that the militia was ready for talks.
"We'll never resort to talks or any deal that is against the interests of the Afghan people," Zabihullah Mujahid told AFP from an undisclosed location.
The Taliban had been in contact with US officials in Qatar about a possible prisoner swap earlier this year, but the militia suspended the talks in March.
In its 9/11 anniversary statement, it called on Americans and their allies "to halt shedding the blood of the oppressed Afghans" and vowed to continue its armed struggle.
The war in Afghanistan has steadily lost popular support in the United States.
A growing majority of Americans oppose the US military presence in Afghanistan and support NATO's plan to withdraw most combat forces by the end of 2014.
More than 2000 US troops have been killed in the war and 77 000 are stationed in Afghanistan.