As an increasing number of suicide attacks rock Pakistan's major cities, concerns for the country's security are rising. In recent years, many new terrorist groups have emerged, several existing groups have reconstituted themselves, and a new crop of militants has emerged, more violent and less conducive to political solutions than their predecessors. Links between many of these new and existing groups have strengthened, say experts, giving rise to fresh concerns for stability. Pakistani authorities have long had ties to militant groups based on their soil that largely focused their efforts in Afghanistan and India. But with Pakistan joining the United States as an ally in its "war on terrorism" since 9/11, experts say Islamabad has seen harsh blowback on its policy of backing militants operating abroad. Leadership elements of al-Qaeda and the Afghan Taliban, along with other terrorist groups, have made Pakistan's tribal areas (the semi-autonomous region along the Afghan border) their home and now work closely with a wide variety of Pakistani militant groups. Security concerns are reverberating beyond Pakistan.  In April 2009, U.S. Secretary of State Hillary Clinton said deteriorating security in nuclear-armed Pakistan "poses a mortal threat" to the United States and the world.

Many experts say it is difficult to determine how many terrorist groups are operating out of Pakistan. Most of these groups have tended to fall into one of the five distinct categories laid out by Ashley J. Tellis, a senior associate at Carnegie Endowment for International Peace, in January 2008 testimony (PDF) before a U.S. House Foreign Affairs subcommittee.

• Sectarian: Groups such as the Sunni Sipah-e-Sahaba and the Shia Tehrik-e-Jafria, which are engaged in violence within Pakistan;
• Anti-Indian: Terrorist groups that operate with the alleged support of the Pakistani military and the intelligence agency Inter-Services Intelligence (ISI), such as the Lashkar-e-Taiba (LeT), the Jaish-e-Muhammad (JeM), and the Harakat ul-Mujahadeen (HuM). This Backgrounder profiles these organizations which have been active in Kashmir;
• Afghan Taliban: The original Taliban movement and especially its Kandahari leadership centered around Mullah Mohammad Omar, believed to be now living in Quetta;
• Al-Qaeda and its affiliates: The organization led by Osama bin Laden and other non-South Asian terrorists believed to be ensconced in the Federally Administered Tribal Areas (FATA). Rohan Gunaratna of the International Centre for Political Violence and Terrorism Research in Singapore says other foreign militant groups such as the Islamic Movement of Uzbekistan, Islamic Jihad group, the Libyan Islamic Fighters Group and the Eastern Turkistan Islamic Movement are also located in FATA;
• The Pakistani Taliban: Groups consisting of extremist outfits in the FATA, led by individuals such as Hakimullah Mehsud, of the Mehsud tribe in South Waziristan, Maulana Faqir Muhammad of Bajaur, and Maulana Qazi Fazlullah of the Tehrik-e-Nafaz-e-Shariat-e-Mohammadi (TNSM).

There are some other militant groups that do not fit into any of the above categories. For instance, secessionist groups such as the Balochistan Liberation Army in the southwest province of Balochistan. BLA was declared a terrorist organization by Pakistan in 2006. Also, a new militant network, often labeled the Punjabi Taliban, has gained prominence after the major 2008 and 2009 attacks in the Punjabi cities of Lahore, Islamabad, and Rawalpindi.

Hassan Abbas, a fellow at the Asia Society, writes the Punjabi Taliban network is a loose conglomeration of members of banned militant groups of Punjabi origin-sectarian as well as those focused on Kashmir-that have developed strong connections with the Pakistani Taliban, Afghan Taliban, and other militant groups based in FATA and the North-West Frontier Province (NWFP).  The Punjabi Taliban provide logistical support for attacks on cities in Punjab province and include individuals or factions of groups such as Jaish-e-Mohammed, Sipah-i-Sahaba Pakistan, and Lashkar-i-Jhangvi and their various splinter groups, along with small cells unaffiliated with any large group. Abbas writes that many of these militants "directly benefited from state patronage in the 1990s and were professionally trained in asymmetrical warfare, guerrilla tactics, and sabotage." The Punjabi Taliban are distinct from the traditional Pashtun Taliban, experts say. They are usually more educated and more technologically savvy.

Since there is also greater coordination between all these groups, say experts, lines have blurred regarding which category a militant group fits in. For instance, the Pakistani Taliban, which were committed to fighting against the Pakistani state, are now increasingly joining insurgents fighting U.S. and international troops across the border in Afghanistan.

Supporters of the Afghan Taliban in the tribal areas transitioned into a mainstream Taliban force of their own as a reaction to the Pakistani army's incursion into the tribal areas, which began in 2002, to hunt down the militants. In December 2007, about thirteen disparate militant groups coalesced under the umbrella of Tehrik-i-Taliban Pakistan (TTP), also known as the Pakistani Taliban, with militant commander Baitullah Mehsud from South Waziristan as the leader. After Mehsud was killed in August 2009 in a U.S. missile strike, his cousin and deputy Hakimullah Mehsud took over as leader of the TTP. Experts say most adult men in Pakistan's tribal areas grew up carrying arms but it is only in the last few years that they have begun to organize themselves around a Taliban-style Islamic ideology pursuing an agenda much similar to that of the Afghan Taliban in Afghanistan. Abbas writes (PDF) in a January 2008 paper that the Pakistani Taliban killed approximately two hundred tribal leaders and effectively established themselves as an alternative.

TTP not only has representation from all of FATA's seven agencies (please refer to this interactive map of the area) but also from several settled districts of the NWFP. According to some estimates, the Pakistani Taliban collectively have around 30,000 to 35,000 members. Among their other objectives, the TTP has announced a defensive jihad against the Pakistani army, enforcement of sharia, and a plan to unite against NATO forces in Afghanistan. Pakistani authorities accused the group's former leader, Baitullah Mehsud, of assassinating former Prime Minister Benazir Bhutto in December 2007. Some experts have questioned the ability of the different groups working under the Pakistani Taliban umbrella to stay united given the rivalries between the various tribes. However, the group has proved since its inception, through a string of suicide attacks, that it poses a serious threat to the country's stability.

Violence in Pakistan has been on the rise as more militant groups target the state. According to South Asia Terrorism Portal (SATP), a terrorism database, 2,155 civilians were killed in terrorist violence in 2008 and nearly 1800 civilians have been killed in the first ten months of 2009 as compared to around 1600 civilian deaths from 2003 to 2006. This new generation of terrorists is also more willing to engage in suicide attacks; journalist Sharmeen Obaid-Chinoy, in a new documentary (CBC), reports that the Taliban are recruiting younger and younger children to carry out suicide attacks. According to SATP, there were nearly sixty suicide attacks in Pakistan in 2009 as compared to only two in 2002. Gunaratna attributes this to the influence of al-Qaeda. He says bin Laden's group is training most of the terrorist groups in FATA. "Al-Qaeda considers itself as the vanguard of the Islamic movement," Gunaratna says, and has introduced its practice of suicide bombings to both the Afghan and the Pakistani Taliban.

Besides providing militant groups in Pakistan with technical expertise and capabilities, al-Qaeda is also promoting cooperation among a variety of them, say some experts. Don Rassler, an associate at the Combating Terrorism Center, an independent research institution based at the U.S. military academy at West Point, writes al-Qaeda "has assumed a role as mediator and coalition builder among various Pakistani militant group factions by promoting the unification of entities that have opposed one another or had conflicting ideas about whether to target the Pakistani state." Carnegie's Tellis says the coordination between these different militant groups is ad-hoc and is driven by necessity. "The important point is that such coordination takes place through the entire spectrum of jihadi groups," he says. "They are much more flexible in their cooperation now than they ever were historically."

Bruce Riedel, the original coordinator of President Obama's policy on the Afghanistan-Pakistan region, in a recent interview to CFR also stressed al-Qaeda's growing cooperation with groups like the Afghan Taliban, the Pakistani Taliban, Lashkar-e-Taiba, and others. "The notion that you can somehow selectively resolve the al-Qaeda problem while ignoring the larger jihadist sea in which [al-Qaeda] swims has failed in the past and will fail in the future," he said.

However, some experts believe that Pakistani Taliban's attacks against the government and the security establishment may have strained their relations with the Afghan Taliban who enjoy close relationship with the army and the ISI, the country's premier intelligence agency. Richard Barrett, a former British intelligence officer who tracks al-Qaeda and the Taliban for the United Nations told the New York Times in October 2009 that the Afghan Taliban "don't like the way that the Pakistan Taliban has been fighting the Pakistan government and causing a whole load of problems there."

Experts say militants have also expanded their control over other parts of Pakistan such as in South Punjab, some settled areas of NWFP, and as far south as Karachi. Military analyst Ayesha Siddiqa writes "South Punjab has become the hub of jihadism (Newsline)."  She argues South Punjabi jihadists have been connected with the Afghan jihad since the 1980s and the majority is still engaged in fighting in Afghanistan. According to some estimates, she says about 5,000 to 9,000 youth from South Punjab are fighting in Afghanistan and Waziristan. According to some experts, the Karachi wing of TTP provides logistics support and recruits new members.

Pakistan's security forces are struggling to confront these domestic militants. As this Backgrounder points out,  efforts are underway to reform the forces but challenges remain both in terms of willingness to fight some of these militant groups as well as capabilities. Security forces, especially the army and the police , have increasingly become the target for the militant groups. In October 2009, militants attacked the army headquarters in Rawalpindi and held around forty people hostage for over 20 hours much to the army's embarrassment.

These attacks have heralded a new period in army and ISI relations with many of these militant groups, say analysts. Steve Coll, president of the New America Foundation, a Washington-based think tank, says since the bloody encounter between Pakistan's security forces and militant Islamic students in Islamabad's Red Mosque in 2007, there has been a pattern of some of these groups previously under state patronage, breaking away from the state. He says Pakistan's security establishment is now trying to figure out how to control them.

Most analysts believe that even though the Pakistani army and the ISI are now more willing to go after militant groups, they continue some form of alliance with groups they want to use as a strategic hedge against India and Afghanistan. But Pakistan's security establishment denies these charges. In October 2009, ISI Chief Ahmad Shuja Pasha said: "The ISI is a professional agency and does not have links  (Daily Times) with any militant outfit including the Taliban."

In particular, U.S. officials would like Pakistan to crackdown on the leadership of the Afghan Taliban believed to be based in Quetta and two major factions of the Afghan insurgency led by veteran Afghan warlords, Jalaluddin Haqqani and Gulbuddin Hekmatyar. These, U.S. officials believe, are actively engaged in supplying fighters in Afghanistan. Analysts believe these groups do not engage in direct attacks against the Pakistani state in lieu of political cover inside Pakistan. Pakistan denies these charges. However, Coll says, there is some shift in Pakistan's strategy of supporting groups against India and to project influence in Afghanistan. "There is more debate and more ambivalence," he says. "Overall, the Pakistani establishment is moving in the right direction but it will take a very long time to undo the pattern that has been established so far."