Sentence:  You may have misgivings about certain aspects of our military establishment - I certainly do - but you know any comparison of over-all American strength with over-all Soviet strength finds the United States not only superior , but so superior both in present weapons and in the development of new ones that our <WSD>advantage</WSD> promises to be a permanent feature of U. S. - Soviet relations for the foreseeable future . 
Meaning of the word marked with <WSD> tags:  the quality of having a superior or more favorable position