TOKYO — The Japanese Army set up a battery of interceptor missiles on the grounds of the Defense Ministry in central Tokyo on Tuesday, as the nation girded itself for a possible missile test by North Korea, maybe as soon as this week.

The Patriot antimissile battery was deployed after the defense minister, Itsunori Onodera, issued standing orders to the Japanese military on Sunday to shoot down any North Korean missile that threatened to hit Japanese territory. Japan has responded to past North Korean tests by similarly issuing such orders and positioning interceptor missiles.

The ministry said warships carrying the Aegis radar and interceptor missiles had been deployed as a shield in waters between the Korean Peninsula and Japan. The Patriot battery, an American-supplied system that is also deployed at two Japanese military bases near Tokyo, will be the second line of defense, the ministry said.

Signs that North Korea may be preparing for a missile test have been met with concern in Japan, which has found itself under the flight path of previous test missiles. In an intensifying war of words with South Korea and the United States, the North has threatened to strike American military bases in Japan. Some of those bases are in the greater Tokyo area, a densely populated urban zone of 33 million people.