I didn't think I'd oppose Bill from NY, but I believe I do on this point. If you see someone in trouble and you are in a position to help out surely you do so without needing an ulterior motive. For example countries from all over the world are helping Pakistan after their devsatating earthquake. They are doing this in no great expectation that Pakistan will ever return the favour (they may do in certain cases such as India or Afghanistan) but because there is a humanitarian need. I'm equally sure that people are not donating help because or despite of Pakistan's nuclear policy or Kashmir policy etc.
Equally the countries that did help after the Katrina hurricane probably did not take into account America's foreign policy in the Middle East (Spain helped - as described by Fernando - and Spain's govt is totally opposed to the US policy in the ME). There may be an element of mutual insurance (if we help in international disasters maybe others will help us if we suffer a calamity) but end of the day it's surely about charity? Or maybe I'm just too naive?