Major Afghan cities have been largely spared from the deadly militant attacks that once struck them regularly.
The Taliban agreed to stop bombing urban centers under a landmark peace deal signed with the United States in February. The militant group largely complied, shifting its focus to the vast countryside, where it has wreaked havoc for months.
But a spate of deadly militant attacks in Kabul has shattered the relative calm in the heavily fortified capital, prompting accusations by Afghan officials that the Taliban had broken its pledge.
The Taliban denied involvement as a local offshoot of the Islamic State (IS) extremist group took responsibility for the mayhem -- which included a pair of attacks that took the lives of dozens of students.
But experts say the attacks were likely carried out by the Haqqani network, the lethal arm of the Taliban. They say the high-profile assaults expose possible divisions within the Taliban over peace efforts aimed at ending the 19-year war in Afghanistan.
A growing number of Taliban leaders, commanders, and factions are opposed to peace, including Sirajuddin Haqqani, the head of the powerful Haqqani network and one of the Taliban's three deputy leaders.
"The attacks in Kabul were carried out mostly, or at least in part, by the Haqqani network without the authorization of the Quetta Shura," says Antonio Giustozzi, a Taliban expert with the Royal United Services Institute in London, referring to the leadership council of the Taliban based in the southwestern Pakistani city of Quetta.
"It is convenient for the Kabul authorities to simply attribute the attacks to the Taliban, but today relations between the Haqqani network and the Quetta Shura are very poor," Giustozzi adds.
A man talks on his phone inside a damaged room at Kabul University following the deadly attack on November 3.
On October 24, a suicide bomber detonated his explosives at the entrance of a tutoring center in Dasht-e Barchi, an area in Kabul mostly populated by the Shi'ite Hazara minority. At least 24 people -- mostly students -- were killed and more than 50 were wounded.
At least 22 people, mostly students, were gunned down during an hours-long assault on Kabul University on November 2, the largest educational institution in the war-torn country.
"The Quetta Shura does not stand to reap any benefit from such attacks in Kabul," Giustozzi says. "If anything, these attacks push the Hazara community to rearm, which is not in the Taliban's interest."
'Tactical Accommodation'
Taliban and IS militants have fought deadly turf wars in Afghanistan since the offshoot appeared in Afghanistan in 2014. But experts say there has also been collaboration between IS and the Haqqani network.
A United Nations report published in June said the IS offshoot "remains capable of mounting attacks in various parts of the country, including Kabul, but some of those claims may have arisen wholly or partly from a tactical accommodation with the Haqqani network."
"We know that IS and the Haqqani network have a close relationship and overlapping membership," says Yelena Biberman, associate professor of political science at Skidmore College in New York. "It is possible that IS and the Haqqani network are working together on this."
Haqqani network militants arrested in Paktia are displayed in January.
Afghan officials have repeatedly alleged collusion between the Taliban and IS militants, casting doubt over the capacity of IS militants to independently execute sophisticated attacks. But U.S. officials have batted away those allegations.
IS militants have continued to claim credit for deadly urban attacks even as the group has been significantly weakened following U.S. air strikes, operations by Afghan forces, and fighting between the Taliban and IS militants in the past year.
The U.S. military said in November that IS strongholds in eastern Afghanistan had been "dismantled" and hundreds of its fighters had surrendered. Afghan officials have also claimed to have arrested several key leaders of the group in recent months.
Split 'Highly Likely'
In an op-ed published in February in The New York Times, Haqqani voiced support for the peace deal with the United States. But experts say Haqqani, who has a $10 million U.S. bounty on his head, is opposed to peace.
Under the U.S.-Taliban agreement, all foreign forces are to leave Afghanistan by May 2021 in return for counterterrorism guarantees from the Taliban, which has pledged to negotiate a permanent cease-fire and a power-sharing agreement with the Afghan government.
The Haqqani network, a U.S.-designated terrorist organization, has close links with Al-Qaeda. Under the deal with the United States, the Taliban pledged to clamp down on foreign terrorists.
The Haqqani network has traditionally had strong ties to Pakistan and Saudi Arabia. But experts say the faction has forged closer ties with Afghanistan's western neighbor, Iran -- a U.S. adversary.
The Haqqanis are among a growing number of Taliban factions to oppose peace.
A breakaway Taliban faction known as the Hezb-e Walayat-e Islami (Party of Islamic Guardianship) split from the mainstream Taliban soon after the deal was reached with the United States.
Other Taliban leaders who oppose the peace efforts include Mullah Qayum Zakir, a powerful battlefield commander and the military chief of the Taliban until 2014. Mullah Zakir leads a Taliban faction along with Ibrahim Sadar, the Taliban's former military commission chief and a powerful field commander.
These factions oppose a more moderate Taliban camp that favors a negotiated end to the war.
Members of the Taliban delegation attend the opening session of the peace talks with the Afghan government in Doha on September 12.
The moderate faction is led by Mullah Mohammad Yaqoob, the new and ambitious military chief who has taken over the group's estimated $1.6 billion business empire.
The young Yaqoob, son of the late Taliban spiritual leader Mullah Mohammad Omar, is believed to want to take over the leadership of the extremist group.
He is backed by Mullah Abdul Ghani Baradar, a co-founder of the Taliban and a former deputy to Mullah Omar. Baradar, who spent years in a Pakistani prison, is the Taliban's political chief and was the lead negotiator in talks with the United States that produced the agreement.
Mullah Yaqoob's appointment was part of the militant group's biggest leadership reshuffle in years and seen as an attempt by leader Mullah Haibatullah Akhundzada to remove potential spoilers and tighten his grip on the group's military and political wings ahead of peace talks with the Afghan government that began in September.
Biberman, the author of Gambling With Violence: State Outsourcing Of War In Pakistan And India, says the rivalry between the Mullah Yaqoob and Haqqani factions is spilling onto the battlefield.
"As violent groups compete for dominance, they often engage in 'outbidding,' using extreme or attention-grabbing violence to signal their strength and commitment to the cause," she says. "This serves to gain the support of those who are uncertain about which group is more likely to deliver on its promises."
Biberman provides the example of Hamas and the Palestinian Islamic Jihad, militant groups that turned to extreme tactics like suicide bombings as a result of the competition they faced from each other and, later, other groups in the region.
Giustozzi, who has written numerous books on the Taliban, says the Haqqani network's split from the mainstream Taliban is "highly likely, unless the Americans suspend the military withdrawal or the intra-Afghan peace talks fully collapse."
'Internal Decision'
Some observers say divisions within the Taliban were not yet visible on the ground.
The Taliban, they say, has remained a relatively coherent fighting force despite succession crises, competition from the global appeal from the IS group, and a deadly war against foreign and Afghan forces for nearly two decades.
Observers say the Taliban has been successful in spinning the peace deal with the United States as an outright victory, helping to keep opposition to the agreement in check.
But the Taliban's unity is likely to be tested when they negotiate the details of a permanent cease-fire and a power-sharing formula with the Afghan government.
The Taliban has pursued a fight-and-talk strategy, hoping to gain leverage in talks with gains on the battlefield. The militants have intensified attacks across Afghanistan even as they negotiate a political settlement with government representatives.
While the Taliban has ramped up pressure on Afghan forces in the countryside, the militant group has also broken its deal with the United States by attacking major cities and highways.
Even before its alleged involvement in attacks in Kabul, the Taliban had launched a brazen offensive in early October to seize control of Lashkar Gah, the second-largest city in southern Afghanistan.
Rahmatullah Amiri, a Kabul-based political analyst, says the Taliban's "push" on the battlefield was an "internal decision by the Taliban," not the work of competing Taliban leaders and factions.
Amiri says the Taliban is united in "applying pressure" on the Kabul government through intensifying attacks.
Even as fighting has sharply increased, Afghan and Taliban negotiators remain deadlocked at the peace talks, unable even to agree on a framework and agenda for the talks.
Members of the Afghan negotiating team have accused the Taliban of stalling the talks by refusing to compromise.