Patriot anti-missile batteries appeared 2009 in the North Koreans capital . They are deployed in case Tokyo carries out its threat to test-fire a missile . Would take five minutes for missile to reach skies over Tokyo . North Korea has deployed these measures before during previous launches .
Patriot anti-missile batteries appeared overnight this week in Japanese capital . They are deployed in case North Korea carries out its threat to test-fire a missile . Would take between five and 10 minutes for missile to reach skies over Tokyo . Japan has deployed these measures before during previous launches .