Tokyo ( CNN ) -- Two PAC 3 Patriot anti-missile batteries currently occupy what is normally a baseball pitch in the leafy grounds of Japan 's Ministry of Defense . They point northwest -- in the general direction of North Korea . They were moved here to the heart of the Japanese capital in the early hours of Tuesday morning , alongside further batteries in two Tokyo suburbs . And if the intelligence is right , and North Korea has moved one , maybe two mid-range missiles to its eastern coast , any test firing it might choose to conduct could conceivably have its trajectory over Japan . Pyongyang is just 800 miles ( 1,287 kilometers ) from Tokyo . It would take between five and 10 minutes for a missile to reach the skies over Tokyo . The concern here is not that North Korea has Japan or indeed any particular target in its sights , whatever its grandiose claims , it is that something might go wrong with a missile test . `` The North Koreans are not trying to attack Japan but to scare the Americans , '' says Narushige Michishita , director of security studies at the National Graduate Institute for Policy Studies ( GRIPS ) in Tokyo . ''The problem is the missile might malfunction and part of the debris might land on Japanese territory . '' Residents whose homes overlook the Ministry of Defense are getting used to these military apparitions outside their bedroom windows . The Patriots have been deployed here three times since 2009 , each time North Korea has announced it will launch what it claims is a satellite , but what most other countries call a missile . `` The situation is acute , '' Japan 's defense minister told the unit commander on a visit to the site laid on for journalists . `` Be ready to take prompt action whenever the order is made . '' It is arguable that this deployment in the heart of the capital is partly for show -- to guarantee photographers an easy front page and thus reassure nervous Tokyoites that their safety is secured . But the missile defense shield the Japanese have developed with the U.S. to safeguard this region is one of the world 's most sophisticated . These latest deployments are about fine-tuning . If the previous three `` satellite '' launches are anything to go by , the Japanese government will have positioned Aegis Destroyers equipped with SM-3 missile interception systems in the Sea of Japan , also known as the East Sea . It has been widely reported that has happened -- though the government wo n't confirm it , unwilling to `` show its cards , '' a spokesman said , to the North Koreans . These deployments should suffice , says Michishita . `` Generally a sea-based system is more useful because it has a wider area it can defend . PAC 3 is more contained but together they are effective . '' But Kim Jong Un 's belligerence has some Tokyo residents clearly worried . Junro Kato came out in search of TV crews like us armed with a map showing how far North Korea 's missiles can reach . `` North Korea can hit Japan in five minutes , '' he said . `` If there are miscalculations between U.S. and North Korea , military conflict will happen . '' For others though , the overriding emotion is astonishment -- astonishment at their puffed up neighbor 's endless posturing .
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 .