Why is 对...不置一词 used like this? 该声明对东盟一些成员国长期以来在南海的大规模填海造地和军事建设活动不置一词。
I am having trouble with 对...不置一词。 So apparently, the sentence translates to, "This statement is not saying anything to stuff the ASEAN member nations have been doing for a long time."  However, the article was about how the Chinese were against other countries doing stuff in their territories. 

Why is 对...不置一词 used here? Does it have a different meaning in this context?
对..不置一词 literally means to 'not place a word on...'.  As Pedroski suggested, it means to not making a comment (or even a word) about the incident.