I object on that.......

When the Muslim army led by prophet mohammed himself, invaded/liberated others lands, they (Muslim Army) used to call their enemy to embrace Islam or face death.
of course, for weak, small enemies they would have no option but to submit to Islam.....isn't this compulsion.....yes it is not in a direct way, but it is still a form of compulsion.

for those people, who surrender without fighting and didn't convert to Islam, they would have to pay "high Taxes" -in arabic: Jiziya", why they should pay taxes? because they are not Muslims.
Again, for poor people who can't afford these Taxes, they wound not have another choice but to convert to Islam.

Now, in every religion, there are 2 kinds of rules: the first is the basic -original rules- put by the founder of the religion. and the second are "opinions" put by people other than the founder, accumulated through time and eventually became substantial religious rules.

nowadays: 2008- location:Mosul-Iraq.
Islamists who control the city force non-muslim minorities to pay extra high Taxes or face death or convert to Islam.
Now, you may say.......OK, they are radical Muslims who practice compulsion in religion, but that is not what Islam is about..........
I would say that would be true if Prophet Mohammed had not practiced it himself. it is a fact that in all many wars Prophet Mohammed led, he practiced compulsion in religion.

Your options are:
fight or convert to Islam
surrender and choose between paying "Taxes" or conversion to Islam

those options were not introduced by Usama Bin Ladin or Al-Thawahiri....those options were introduced and practiced by prophet Mohammed....which makes them basic rules.

Hint: I am not judging whether compulsion in religion is a good or a bad thing....I am just saying: compulsion in religion exists in Islam -not just as a personal practice by radicals, but as a basic constitutional rule-