He specifically cited presence of non-Muslim troops in the Arabian Peninsula, it was presented as the number 1 justification for al Qaeda’s declaration of war on America:
“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...
...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.”
https://fas.org/irp/world/para/docs/980223-fatwa.htm