http://www.fas.org/irp/world/para/docs/980223-fatwa.htm 
FAS Note: The following statement from Usama bin Laden and his associates purports to be a religious ruling (fatwa) requiring the killing of Americans, both civilian and military. This document is part of the evidence that links the bin Laden network to the September 11 terrorist attacks on New York and Washington. The original Arabic text of this statement may be found here.
We -- with Allah's help -- call on every Muslim who believes in Allah and wishes to be rewarded to comply with Allah's order to kill the Americans and plunder their money wherever and whenever they find it. We also call on Muslim ulema, leaders, youths, and soldiers to launch the raid on Satan's U.S. troops and the devil's supporters allying with them, and to displace those who are behind them so that they may learn a lesson.Jihad Against Jews and Crusaders
World Islamic Front Statement
23 February 1998
Shaykh Usamah Bin-Muhammad Bin-Ladin
Ayman al-Zawahiri, amir of the Jihad Group in Egypt
Abu-Yasir Rifa'i Ahmad Taha, Egyptian Islamic Group
Shaykh Mir Hamzah, secretary of the Jamiat-ul-Ulema-e-Pakistan
Fazlur Rahman, amir of the Jihad Movement in Bangladesh
Praise be to Allah, who revealed the Book, controls the clouds, defeats factionalism, and says in His Book: "But when the forbidden months are past, then fight and slay the pagans wherever ye find them, seize them, beleaguer them, and lie in wait for them in every stratagem (of war)"; and peace be upon our Prophet, Muhammad Bin-'Abdallah, who said: I have been sent with the sword between my hands to ensure that no one but Allah is worshipped, Allah who put my livelihood under the shadow of my spear and who inflicts humiliation and scorn on those who disobey my orders.
The Arabian Peninsula has never -- since Allah made it flat, created its desert, and encircled it with seas -- been stormed by any forces like the crusader armies spreading in it like locusts, eating its riches and wiping out its plantations. All this is happening at a time in which nations are attacking Muslims like people fighting over a plate of food. In the light of the grave situation and the lack of support, we and you are obliged to discuss current events, and we should all agree on how to settle the matter.
No one argues today about three facts that are known to everyone; we will list them, in order to remind everyone:
All these crimes and sins committed by the Americans are a clear declaration of war on Allah, his messenger, and Muslims. And ulema have throughout Islamic history unanimously agreed that the jihad is an individual duty if the enemy destroys the Muslim countries. This was revealed by Imam Bin-Qadamah in "Al- Mughni," Imam al-Kisa'i in "Al-Bada'i," al-Qurtubi in his interpretation, and the shaykh of al-Islam in his books, where he said: "As for the fighting to repulse [an enemy], it is aimed at defending sanctity and religion, and it is a duty as agreed [by the ulema]. Nothing is more sacred than belief except repulsing an enemy who is attacking religion and life."First, for over seven years the United States has been occupying the lands of Islam in the holiest of places, the Arabian Peninsula, plundering its riches, dictating to its rulers, humiliating its people, terrorizing its neighbors, and turning its bases in the Peninsula into a spearhead through which to fight the neighboring Muslim peoples.
If some people have in the past argued about the fact of the occupation, all the people of the Peninsula have now acknowledged it. The best proof of this is the Americans' continuing aggression against the Iraqi people using the Peninsula as a staging post, even though all its rulers are against their territories being used to that end, but they are helpless.
Second, despite the great devastation inflicted on the Iraqi people by the crusader-Zionist alliance, and despite the huge number of those killed, which has exceeded 1 million... despite all this, the Americans are once against trying to repeat the horrific massacres, as though they are not content with the protracted blockade imposed after the ferocious war or the fragmentation and devastation.
So here they come to annihilate what is left of this people and to humiliate their Muslim neighbors.
Third, if the Americans' aims behind these wars are religious and economic, the aim is also to serve the Jews' petty state and divert attention from its occupation of Jerusalem and murder of Muslims there. The best proof of this is their eagerness to destroy Iraq, the strongest neighboring Arab state, and their endeavor to fragment all the states of the region such as Iraq, Saudi Arabia, Egypt, and Sudan into paper statelets and through their disunion and weakness to guarantee Israel's survival and the continuation of the brutal crusade occupation of the Peninsula.
On that basis, and in compliance with Allah's order, we issue the following fatwa to all Muslims:
The ruling to kill the Americans and their allies -- civilians and military -- is an individual duty for every Muslim who can do it in any country in which it is possible to do it, in order to liberate the al-Aqsa Mosque and the holy mosque [Mecca] from their grip, and in order for their armies to move out of all the lands of Islam, defeated and unable to threaten any Muslim. This is in accordance with the words of Almighty Allah, "and fight the pagans all together as they fight you all together," and "fight them until there is no more tumult or oppression, and there prevail justice and faith in Allah."
This is in addition to the words of Almighty Allah: "And why should ye not fight in the cause of Allah and of those who, being weak, are ill-treated (and oppressed)? -- women and children, whose cry is: 'Our Lord, rescue us from this town, whose people are oppressors; and raise for us from thee one who will help!'"
We -- with Allah's help -- call on every Muslim who believes in Allah and wishes to be rewarded to comply with Allah's order to kill the Americans and plunder their money wherever and whenever they find it. We also call on Muslim ulema, leaders, youths, and soldiers to launch the raid on Satan's U.S. troops and the devil's supporters allying with them, and to displace those who are behind them so that they may learn a lesson.
Almighty Allah said: "O ye who believe, give your response to Allah and His Apostle, when He calleth you to that which will give you life. And know that Allah cometh between a man and his heart, and that it is He to whom ye shall all be gathered."
Almighty Allah also says: "O ye who believe, what is the matter with you, that when ye are asked to go forth in the cause of Allah, ye cling so heavily to the earth! Do ye prefer the life of this world to the hereafter? But little is the comfort of this life, as compared with the hereafter. Unless ye go forth, He will punish you with a grievous penalty, and put others in your place; but Him ye would not harm in the least. For Allah hath power over all things."
Almighty Allah also says: "So lose no heart, nor fall into despair. For ye must gain mastery if ye are true in faith."