Sentence:  Essentially this imposed two conditions : First , international law had to recognize and be compatible with an international political system in which a number of states were competitive , suspicious , and opportunistic in their political <WSD>alignments</WSD> with one another ; second , it had to be compatible with the value system that they shared . 
Meaning of the word marked with <WSD> tags:  an organization of people (or countries) involved in a pact or treaty