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In January this year , North Korea withdrew from the Nuclear Nonproliferation Treaty , a global accord to prevent the spread of nuclear weapons .
 North Korea, Nuclear, nuclear, nuclear weapons
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: organization, person, geographical social political, vehicle, location, weapon, facility 
Text: {0} 
Answer:
 North Korea, Nuclear, nuclear, nuclear weapons