Sentence:  `` Quoting Mr. Kennan 's phrase that anything would be better than a policy which led inevitably to nuclear war , he [ Toynbee ] says that anything is better than a policy which <WSD>allows</WSD> for the possibility of nuclear war '' . 
Meaning of the word marked with <WSD> tags:  make a possibility or provide opportunity for; permit to be attainable or cause to remain