A major neutral country was, as an example, Yugoslavia (the leader non-aligned movement), which supported trade relations with both NATO and the Warsaw Pact. In the later years of the Cold War, China, became mostly neutral (though some may say that they became more Western Aligned). Throughout the Cold War, India officially didn't join any alliance, however they were often supported by the Soviet Union in conflicts against China or Pakistan.
Answer:
After the attack on Pearl Harbor and America declared war on Japan, it was suspected that there could be Japanese spies within the US.
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