Q & A: Who are the Pakistani Taliban insurgents?

A suicide car bomber attacked an office of Pakistan's main intelligence agency in the northwestern city of Peshawar today, killing 10 people and wounding 60, officials said.

There was no claim of responsibility but Pakistani Taliban militants have in recent weeks stepped up bomb attacks in retaliation for an army offensive against their South Waziristan stronghold, launched on Oct. 17.

Here are some questions and answers about the Pakistani Taliban:

WHO ARE THE PAKISTANI TALIBAN?

Most Pakistani Taliban fighters are ethnic Pashtuns from northwestern regions on the Afghan border. They support the Afghan Taliban, most of whom are also Pashtun and many of whom fled to the Pakistani Pashtun lands after U.S.-led forces ousted Afghanistan's hardline Taliban government in late 2001.

More than a dozen factions based in different parts of northwest Pakistan formed a loose umbrella group, the Tehrik-e-Taliban Pakistan (TTP), or Taliban Movement of Pakistan, led by Baitullah Mehsud in late 2007. Mehsud was killed by a missile-firing U.S. drone aircraft in South Waziristan in August.

He was replaced by Hakimullah Mehsud. Mehsud is a Pashtun tribal name and is used by many members of the tribe as a last name. Estimates of the strength of Mehsud's faction alone vary from about 10,000 fighters to more than 20,000.

Baitullah Mehsud was accused of plotting numerous bomb attacks after the army stormed Islamabad's Red Mosque in July 2007 to crush a militant movement there. But it was when the government named him the chief suspect in the assassination of former Prime Minister Benazir Bhutto in 2007 that his notoriety rocketed.

While many senior Taliban are veterans of Afghan fighting, they have exploited poverty, frustration over an ineffective judiciary, anger against landlords and widespread anti-U.S. feeling to attract recruits. Intelligence officials say they also press families to send sons to fight.

ARE THE PAKISTANI TALIBAN LINKED TO AL QAEDA?

Intelligence officials and security experts say the Pakistani Taliban have grown increasingly close to their al Qaeda ally. Baitullah Mehsud gave refuge to many foreign militants, including Arabs and Central Asians. While helping al Qaeda, Mehsud and his successor have focused their attacks on Pakistan and its security forces.

WHAT IS THE RELATIONSHIP WITH THE AFGHAN TALIBAN?

The TTP swears allegiance to Mullah Omar, chief of the Taliban in Afghanistan, and sends fighters across the border to Afghanistan. The Afghan Taliban are fighting what they call Western "occupation" forces. The Pakistani Taliban support that and also want their version of Islamist rule in Pakistan. There are differences between militant factions on whether to fight Pakistani security forces. Some oppose violence in Pakistan and want all Taliban to focus on Afghanistan. But leaders such as the Mehsuds argued that fighting Pakistani forces was justified because of Pakistan's support for the U.S.-led campaign against al Qaeda and the Afghan Taliban.

Three major Taliban commanders on the border are Maulvi Nazir Wazir, Hafiz Gul Bahadaur and Jalaluddin Haqqani. They are not in the TTP and are known for attacks in Afghanistan, not in Pakistan. The military has declined to comment on news reports that deals have been struck to keep those factions out of the battle in South Waziristan.

Security analysts say some Pakistani Taliban fighters appear to be fleeing the army offensive and taking refuge with their allies in places such as North Waziristan from where they are likely to continue their campaign against the state.