Authorities in Japan are on high alert as Wednesday is the first day of the period during which North Korea says it will launch what it calls a "satellite." Japanese officials say they believe North Korea will use ballistic missile technology for the launch, and it is possible the projectile would pass above Japan's southwestern prefecture of Okinawa.

Pyongyang notified the Japan Coast Guard on Monday of its plan to launch a satellite between Wednesday and June 11.

A senior official of the ruling Workers' Party said on Tuesday that the launch of its first military spy satellite will happen in early June.

Japan's government says North Korea has not issued any notice of a change in the launch window and that the firing could happen on Wednesday.

Japan's Chief Cabinet Secretary Matsuno Hirokazu said that a satellite launch involves the use of technology that is almost the same as, and is compatible with, the technology used to fire ballistic missiles.

He said the government believes North Korea will use its ballistic missile technology, regardless of how it describes the launch, and any launch by Pyongyang violates UN Security Council resolutions.

Japan is working with relevant countries to urge Pyongyang to exercise self-restraint.

Japan's government says the projectile could fly over an area close to the Sakishima Islands in Okinawa Prefecture and that it is prepared to issue evacuation information promptly. The alert will be issued through the J-Alert emergency warning system.

Japan's Defense Minister Hamada Yasukazu ordered the Self-Defense Forces to destroy any projectile fired by North Korea in the event that part of it is likely to fall within Japanese territory.

Destroyers equipped with the Aegis missile-tracking system, which has advanced radar and interceptor missiles, are on standby around the clock in the East China Sea.

Land-based PAC-3 interceptor systems have been deployed in Naha City and on the Sakishima Islands in Okinawa Prefecture, as well as the premises of the Defense Ministry in Tokyo.

The Ground Self-Defense Force has sent units to Okinawa that are tasked with removing hazardous materials and rescuing injured people in the event of a ballistic missile falling in the area.

It is possible that a de facto ballistic missile could pass over Okinawa Prefecture about 10 minutes after its launch.