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...