ST, I am neither a judge nor a policy maker, but IMHO the basis of foreign aid is found in "General Welfare" and "Common Defense".
Registerd, Stratgic Interest is the correct answer. Now we all know that the pre 911 Bush was not going to increase foreign aid. In fact, he didn't announced his policy change until this spring, with a lot of prodding by Congress.
It is in the stratigic interest of the US to prevent Islam from penetrating further into Africa.