A wave of attacks on the Afghan army and police and U.S. special forces in Kabul have killed at least 50 people and wounded hundreds, dimming hopes that the Taliban might be weakened by a leadership struggle after their longtime leader's death.
The bloodshed began on Friday with a truck bomb that exploded in a heavily populated district and included an hours-long battle at a base used by U.S. special forces. It became the deadliest day in Kabul for years.
The Islamist insurgents claimed responsibility for both the police academy attack and the battle at the U.S. special forces base, though not for the truck bomb.
The violence was a reminder of the difficulty of reviving a stalled peace process, conveying a no-compromise message from the Taliban following the late July revelation of Mullah Mohammad Omar's death and a dispute over the leadership of the insurgency.
"The question is, who is sending the message?" said Thomas Ruttig of the Afghanistan Analysts Network.
The U.N. mission in Afghanistan said Friday was the most violent day since it began recording civilian casualties in 2009, with 355 civilians killed or injured.
On Saturday, NATO-led coalition forces confirmed that one international force member and eight Afghan contractors had been killed in the attack on Camp Integrity, a base used by U.S. special forces near the airport.
The blast outside the base was powerful enough to flatten offices inside, wounding occupants who were airlifted by helicopter to military hospitals.
"There was a big explosion at the gate ... (The gunfire) sounded like it came from two different sides," said a special forces member who was wounded when his office collapsed.
The initial blast caused by a suicide car bomb at the gate was followed by other explosions and a firefight that lasted a couple of hours, he said.
"The helicopters went on for hours ... medevac-ing people out," a U.S. contractor at a camp nearby said.
A U.S. spokesman for the NATO mission in Afghanistan said the Taliban had increasingly turned to high profile attacks.
"The recent attacks in Kabul are consistent with this trend," said the spokesman, Brigadier General Wilson Shoffner.
Camp Integrity is run by U.S. security contractor Academi, which was known as Blackwater before being sold to investors. It said eight Afghans contracted to a local partner security firm were killed. It declined to comment further.
In Washington, the White House said National Security Advisor Susan Rice had spoken with Afghan President Ashraf Ghani by telephone to express U.S. condolences.
The Camp Integrity assault followed a suicide bombing at a police academy on Friday evening that killed and wounded more than 40 people, the Interior Ministry said. A police source said the final tally was higher - 26 killed and 28 wounded.
"The bomber was wearing a police uniform and detonated his explosives among students who had just returned from a break," a police official said.
Taliban spokesman Zabihullah Mujahid said the insurgents had launched both the police academy and Camp Integrity attacks, but not Friday's truck bomb, which tore through buildings in central Kabul, killing at least 15 people and wounding 248.
The Taliban, who were toppled from power by a U.S.-led military intervention in 2001, rarely admit to attacks that kill a high number of civilians.
The insurgents also struck in the north, claiming responsibility for a suicide attack in Kunduz province on Saturday that killed 22 members of a militia backing the government.
Divisions have broken out within the Taliban high command following the appointment of Mullah Akhtar Mansour as leader. Previously seen as open to reviving peace talks, he has since pledged to press on with the insurgency, which has killed or wounded thousands this year.
The conflict between the Western-backed government and the Taliban has intensified since the NATO combat mission ended last year, but Afghan security forces and civilians have borne the brunt of the violence.
Analyst Ruttig said that, with the latest attacks in Kabul, Mansour could be sending a message of resolve to the militant rank and file as well as to the Afghan government.
On the other hand, Taliban factions opposing Mansour's leadership could be seeking to kill off any hope of talks by launching the violence.
"The hope of some people was that the death of Mullah Omar would put the Taliban in disarray and possibly weaken them," Ruttig said. "I think that was a little over-optimistic."
The death at Camp Integrity was the second of an international service member in Afghanistan this year. The victim's nationality was not released.
Almost 5,000 civilians were killed or wounded in the first half of the year, according to U.N. figures.