This story proves the involvement of Pakistan's secret service (the ISI) in the September 11 attacks:
SEPT. 11'S SMOKING GUN: THE MANY FACES OF SAEED SHEIKH
Paul Thompson, Unansweredquestions.com, September 4, 2002, updated February 25, 2003

["If you read just one thing at this website, please read this essay. Don't mind the length and complexity. Saeed Sheikh's story is not just mildly interesting. Understanding the history of this young man may not only explain many mysteries of 9/11, including solid evidence of foreign government involvement in the attacks, but may also reveal if nuclear war in the near future is likely. Please read! Note that this was first written in September 2002 but has been thoroughly overhauled based on exposure to additional evidence.
Also, click to find more details about [Khalid Sheikh Mohammed], Saeed Sheikh and his boss ISI Director Mahmood Ahmed."]

As the London Times has put it, Saeed Sheikh "is no ordinary terrorist but a man who has connections that reach high into Pakistan's military and intelligence elite and into the innermost circles of Osama Bin Laden and the al-Qaeda organization." [London Times, 4/21/02] To appreciate why Saeed is so important in comprehending 9/11,

--it is necessary to first understand Pakistan's intelligence agency, the Inter-Services Intelligence (ISI). The ISI plays a much more significant role in the Pakistani government than do its counterparts in other countries. Time Magazine has noted, "Even by the shadowy standards of spy agencies, the ISI is notorious. It is commonly branded 'a state within the state,' or Pakistan's 'invisible government.'" [Time, 5/6/02] The ISI grew into its present form during the war between the Soviet Union and mujaheddin guerrillas in Afghanistan during the 1980s.

The CIA thought the Afghan war could be Russia's own costly Vietnam War, and it funneled billions to the mujaheddin resistance to keep it a thorn in Russia's side. The strategy worked: Soviet soldiers withdrew from Afghanistan in 1989, and the Soviet Union collapsed two years later, partly due to the costs of the war. [Pittsburgh Post-Gazette, 9/23/01]

But the costs to keep the mujaheddin fighting were staggering, with estimates ranging between $6 billion and $40 billion. [New York Times, 8/24/98, Nation, 2/15/99] While a substantial portion of this amount came from the CIA and the Saudi Arabian government, who were both funneling the money through the ISI, much of the cost was deferred by Afghanistan's opium trade.
[...]

The ISI Muzzled? No

Musharraf has been hailed for his firing of ISI Director Mahmood, and generally has been presented as a pro-Western figure trying to root out pro-terrorist factions of the ISI. But the Observer has called this "The Myth of the Good General Musharraf." [Observer, 3/31/02]
[...]

PROFILES:
-- ISI Director Mahmood Ahmed

-- 9/11 Mastermind Khalid Shaikh Mohammed
--[arrested March 1, 2003: see story of his arrest]

-- 9/11 Paymaster Saeed Sheikh

A CHRONOLOGY:
-- Pakistan ISI and/or Drug Connections

THE STORY:
-- The Journalist and The Terrorist: Daniel Pearl and Ahmed Omar Saeed Sheikh
Robert Sam Anson,Vanity Fair, August, 2002

--Khalid Shaikh Mohammed: Al Qaida Suspect Flown Out of Pakistan
Anwar Iqbal, United Press International, March 2, 2003
- posted by ARYABHATT @ 5:58 pm