Monday's mosque bombing in northwestern Pakistan has underscored a resurgence in militant attacks in recent months in the South Asian nation.
No one has claimed responsibility for the attack, in which more than 90 people were killed, but officials believe it was launched by Islamist militants.
Here are some facts about the militant threat faced by the economically and politically unstable nuclear-armed country of 220 million.
Pakistani Taliban
* The principal threat to Pakistan is an organisation called the Tehreek-e-Taliban Pakistan (TTP), which was formed in 2007 as umbrella organisation of various hardline Sunni Islamist groups operating individually in Pakistan.
* TTP, also known as the Pakistani Taliban, pledges allegiance to, and gets its name from, the Afghan Taliban, but is not directly a part of the group that now rules neighbouring Afghanistan. Its stated aim is to impose Islamic religious law in Pakistan, as the Taliban have done in Afghanistan.
* TTP was headquartered in Pakistan's erstwhile tribal areas, that were long a hotbed for militant groups, including al Qaeda, whose members fled Afghanistan after the U.S.-led invasion in 2001.
* The TTP is responsible for some of the bloodiest attacks in Pakistan, including on churches, schools and the shooting of Malala Yousafzai, who survived the 2012 attack after she was targeted for her campaign against the Taliban's efforts to deny women education.
* Pakistani forces were able to effectively dismantle the TTP and kill most of its top leadership in a string of military operations from 2014 onwards in the tribal areas, driving most of the fighters into Afghanistan, where they regrouped.
* They have been buoyed by the victory of the Afghan Taliban in Afghanistan over the U.S.-backed government after western forces exited the country in 2021.
* There was an attempt by Pakistan to hold peace talks with the TTP, resulting in a months-long ceasefire and negotiations brokered by the Afghan Taliban. The plan fell through, and a regrouped TTP restarted attacks in Pakistani late last year.
* Pakistan says the TTP leadership has safe havens in Afghanistan, but the Afghan Taliban administration denies this. The rise in TTP attacks has increased tensions between Islamabad and the Taliban administration.
* TTP attacks are mostly directed at Pakistan, unlike the other big militant threat in the region, Islamic State.
Islamic State in Khurasan
* The Islamic State in Khurasan (IS-K) is an affiliate of the Middle East-based Islamic State in Iraq and Syria (ISIS). Khurasan refers to the historic name of the region between Iran, Afghanistan and Central Asia.
* It is unclear how much control ISIS exerts over IS-K, but the main group does claim the attacks carried out in Afghanistan and Pakistan. Its stated aim is to impose an Islamic Caliphate in the region.
* IS-K has been more active in Afghanistan than in Pakistan. In Afghanistan, it has emerged as the principal threat to the Taliban administration's efforts to impose peace.
* One of the group's major attacks in Pakistan came last year when it bombed a Shi'ite mosque in Peshawar.
* IS-K subscribes to a different school of Islamic thought than the TTP. It considers the Taliban and their associates apostates.
* Its presence is much smaller than the TTP in Pakistan, but it has ideologically committed members who operate clandestinely from the cities and are said to have infiltrated various spheres of society, presenting an entirely different problem from the TTP ground forces.
* There have been reported defections from the TTP into IS-K and some splinter cells have started to work closely together.
* IS-K presents a wider international problem having attacked foreign targets, including a bombing of Kabul airport in 2021 that killed U.S. soldiers, as well as attacks on Chinese citizens in Afghanistan.
(Reporting by Gibran Peshimam; Editing by Nick Macfie)
