Pakistani warlord Baitullah Mehsud threatened to attack Washington and the White House, as he claimed responsibility on Tuesday for this week's assault on the police training academy in Lahore.

    Mehsud leads the biggest faction of the Pakistani Taliban, an Islamic militia, operating in the lawless South Waziristan tribal region that borders Afghanistan. Mehsud's violent faction is the biggest challenge to the very existence of the Pakistani state, which has been under sustained attack by the Taliban and other extremists for months.

    Fighters loyal to Mehsud also cross the border to battle U.S. and NATO forces in Afghanistan. Earlier this month, the U.S. put a $5 million bounty on his head, describing him as a key commander of al Qaida.

    The Pakistani Taliban have no known capability to stage attacks in Washington or elsewhere in the west, although al Qaida could facilitate such an operation for them, said Asad Munir, the former head of military intelligence for northwest Pakistan.

    That fact isn't dampening Mehsud's bluster.

    "We wholeheartedly take responsibility for this attack and will carry out more such attacks in future," said Mehsud, speaking with Reuters news agency by phone from his hideout. "It's revenge for the (U.S.) drone attacks in Pakistan."

    The CIA operates pilotless "drone" aircraft that have repeatedly fired missiles at suspected militants in the tribal area including, more recently, the area under the control of Mehsud.

    Mehsud warned the U.S. that, "You can't imagine how we could avenge this threat inside Washington, inside the White House." Separately, Mehsud told the Associated Press: "Soon we will launch an attack in Washington that will amaze everyone in the world."

    At least 12 people were killed on Monday when a squad of heavily armed militants stormed the police training school on the outskirts of Lahore, spraying it with gunfire and grenades. Nearly 100 were injured.

    There was also a rival claim for the attack from a little-known group, Fedayeen al Islam, which previously took responsibility for the September bombing of the Marriott hotel in the capital, Islamabad. Mehsud's proclamation of guilt, which jibes with the initial government investigation, was the one taken seriously, however.

    Munir, the retired intelligence officer, said that Mehsud wanted to emulate Mullah Omar, the founder of the Afghan Taliban.

    Mehsud "wants power. He's not going to lay down arms even if NATO forces leave Afghanistan," Munir said. "He thinks that, if Mullah Omar can rule Afghanistan, he can rule part of Pakistan."

    Mehsud has consistently said that he recognizes Omar as his ultimate leader. Omar, when in power in Afghanistan between 1996 and 2001, had sheltered Osama bin Laden, the al Qaida leader, provoking the U.S.-led invasion of Afghanistan after the Sept. 11, 2001, attacks.

    Omar is said to still be instrumental in directing the Taliban in its insurgency against international forces in Afghanistan.

    By offering guns and employment to young members of his native Mehsud tribe, a powerful clan in South Waziristan, Baitullah Mehsud has built a following of thousands of armed supporters.

    Virtually unknown as recently as 2004, he terrorized anyone who opposed him, including the chiefs of his own tribe.

    Mehsud consolidated his power in umbrella group, Tehreek-e-Taliban Pakistan, which brought together most of the Pakistani Taliban outfits in late 2007. The Tehreek-e-Taliban's control of territory now stretches across the tribal area and into Swat, a valley in the northwest.

    A copycat of the Afghan Taliban movement, it emerged in response to Pakistan's alliance with the U.S. and with other western countries after 9/11. It trains suicide bombers to carry out missions across Pakistan.

    In recent years, the Pakistani Taliban became deeply influenced by al Qaida and its creed of relentless violence and global jihad. In particular, the Pakistani Taliban took up al Qaida's justification for killing fellow Muslims, who've been almost exclusively its target.

    Mehsud was accused by Islamabad of carrying out the assassination of the former prime minister Benazir Bhutto in December 2007; he denied the charge.

    Despite the threat that Mehsud poses to Pakistan, the country's army is not fighting him. Instead, it signed a secret truce with the warlord early last year, a deal that concerns the West. Munir said that Pakistan "does not have the firepower available" to tackle Mehsud. That means that, in the near term, the best chance of eliminating the warlord is through a successful strike by a U.S. drone.

    Under al Qaida's tutelage, Pakistani Islamic radicals turned on their own country, arguing that it is serving American interests. The al Qaida group now largely operates through its Pakistani partners, such as the Taliban, experts think.

    "At some level, they (al Qaida and Pakistani Taliban) have coordination, they have some kind of pool, where they contribute what they have: logistics, training, capability, finance, human resources," said Muhammed Amir Rana, director of the Pak Institute for Peace Studies, an independent research organization in Islamabad.

    "When al Qaida or the (Afghan) Taliban or the Pakistani Taliban, have the same targets, the same objectives, almost the same the same political agenda, how can you differentiate between them?"