Sentence:  One of the paradoxes of Ostpolitik, as practiced by Brandt and his successors, was that by transferring large sums of hard currency into East Germany and showering the GDR with recognition, attention, and support, West German officials unintentionally <WSD>foreclosed</WSD> any chance of internal change, including reform of Eastern Germany's polluted, antiquated industrial economy. 
Meaning of the word marked with <WSD> tags:  To shut up or out; to prevent from doing something.