Sentence:  As a nation , we feel an <WSD>obligation</WSD> to assist other countries in their development ; but this obligation pertains only to countries which are honestly seeking to become responsible members of a stable and forward-moving world community . 
Meaning of the word marked with <WSD> tags:  the social force that binds you to the courses of action demanded by that force; every opportunity, an obligation; every possession, a duty"- John D.Rockefeller Jr