In countering Al-Sharif, Al-Zawahiri contends that "we have the right to do to the infidels what they have done to us. We bomb them as they bomb us, even if we kill someone who is not permitted to be killed." He compares the &lt;a href="9/11%20attack"&gt;9/11 attack&lt;/a&gt; to the 1998 American bombing of a pharmaceutical plant in Sudan: "I see no difference between the two operations, except that the money used to build the factory was Muslim money and the workers who died in the factory's rubble [a single night watchman] were Muslims, while the money that was spent on the buildings that those hijackers destroyed was infidel money and the people who died in the explosion were infidels."