The group claiming responsibility for the Easter Sunday attack on a mostly Christian group in Pakistan is Jamaat-ul-Ahrar, a breakaway faction of the Pakistani Taliban that publicly supports the Islamic State.
But those who follow these extremist groups closely say while Jamaat-ul-Ahrar broke away from the Pakistani Talibani two years ago, it is virtually indistinguishable from the larger movement — even though in this case, it may have been following its own agenda.
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"These guys are demonstrating that, yes there's a military offensive against them, yes they're on the run, yes they've been dislodged from their hideouts, but they still retain their capability," says Kamran Bokhari, a fellow with the Program on Extremism at George Washington University.
And while there has been a marked decrease in the number of extremist attacks in Pakistan since 2014, Bokhari says, many groups in this "saturated" market still have the "assets" to stage a big attack and are keen to show they haven't given up.
"They don't have to attack as frequently as they used to, as long as they can attack periodically and in different places around the country, they can demonstrate that they're still alive and kicking."
Pakistan is in the midst of three days of national mourning after a massive suicide bombing on Easter Sunday targeted Christians and killed at least 70 people gathered in a popular park in the northeast city of Lahore.
While the group has said it was targeting Pakistan's Christian minority, many Muslims were among those killed when a suicide bomber set off a nail-filled device next to a playground.
Here's what we know about Jamaat-ul-Ahrar:
Not a 'cohesive organization'
"They're much more of a faction than a splinter," says Scott Stewart, vice-president of tactical analysis with Stratfor, a global intelligence and advisory firm based in Austin, Texas.
"It's important to understand that the Pakistan Taliban really isn't one cohesive organization."
In fact, Pakistan's militant groups are so fragmented that few Pakistanis will even recognize Jamaat-ul-Ahrar's name, adds Christine Fair, a professor with Georgetown University's security studies program.
"The English media will talk about this 'new faction,' but the Urdu media will not bother making this distinction," she says. "I learned long ago that the names of these groups are less important than the actual commanders."
Most of these militants and groups are "loosely networked," Fair says, and may conduct operations elsewhere, with other affiliates, depending on the conditions.
"Imagine flecks in a kaleidoscope. You shake it once, you look at it … You shake it again, you get a different picture."
Sunday's blast was Jamaat-ul-Ahrar's fifth bombing since December, according to Reuters.
Jamaat-ul-Ahrar also claimed responsibility for a pair of suicide attacks in March 2015 at two Christian churches in Lahore, killing 15 and wounding dozens more.
It was also linked to a suicide bombing that killed 60 during a flag-lowering ceremony at the Wagah border crossing with India in November 2014, though three different groups have claimed responsibility.
Pakistan's history of using jihad as a foreign policy tool has helped create the fragmented extremist landscape of today, Fair suggests.
"The Pakistani Taliban is itself the product of several other militant groups that Pakistan has nurtured – and in some cases explicitly raised — over the last several decades," she says.
Fair says the Pakistani Taliban would not exist were it not for two other groups: the Jaish-e-Mohammed, an Islamist group established in the early 2000s that claims to be fighting a holy war against Indian rule in Kashmir. And the Lashkar-e-Jhangvi, one of Pakistan's most vicious groups, which follows an anti-Shia branch of Islamic extremists.
The common factor is that all of these groups — including the TTP and Jamaat-ul-Ahrar — are part of a revival of an extremely conservative branch of Sunni Islam called Deobandi.
After 9/11, when Pakistan aided the U.S. invasion to oust the Afghan Taliban, these groups turned against the state, as the Afghan Taliban was the primary organization in the region based on Deobandi principles.
That grouping provided the early origins of the Pakistani Taliban, which wasn't formalized until 2007.
"One of the most important things that people don't appreciate about the TTP [the Pakistani Taliban] is that many of its commanders are Lashkar-e-Jhangvi," says Fair.
"Their agenda has always been communal, meaning going after non-Muslims, and sectarian, going after the kinds of Muslims that they believe are not proper Muslims."
Fair says that while the Jamaat-ul-Ahrar can be viewed as an offshoot of the TTP, she sees it as some of these Lashkar-e-Jhangvi commanders returning to their sectarian hatreds.
"And it explains why it has been so sectarian in its targeting."
Destabilizing effect of Mullah Omar's death
Fair says the Pakistani Taliban has never had the same leadership cohesion that the Afghan Taliban had under its founder, Mullah Mohammed Omar.
But Fair says the announcement of the Taliban founder's death last July — two years after his 2013 death in Pakistan — further destabilized the TTP movement.
Some commanders who were sticking around for loyalty's sake began defecting to other groups, including ISIS, with a more sectarian agenda.
"As long as Mullah Omar was alive … it was considered impolitic to defect," she says. "Omar's death really created an opportunity space for many of these organizations to run over to ISIS."
2014 military crackdown
The government of Pakistan has been trying to distance itself from the Taliban and other extremist groups, partly as a result of two events that triggered international outrage.
The TTP claimed responsibility for the 2012 attack on then-14-year-old Malala Yousafzai (who went on to win the Nobel Prize for her refusal to back down) and then the Peshawar school massacre of 134 children at an army-run school in December 2014.
Soon after the Peshawar incident, the Pakistani military bombed the border areas in North Waziristan, trying to root out extremists.
But the Pakistan military's history of trying to either leverage these groups to do some of its bidding — or at least turning a blind eye to them — has created a "significant, deeply rooted" problem, says Stewart.
He notes that many of these radicals have connections within Pakistan's military and intelligence services.
"Because they had this policy of the 'good Taliban' and the 'bad Taliban,' and saying we'll support the good and attack the bad — that really hasn't worked for them," says Stewart.
"What we've seen is Frankstein's monsters attacking him."