Systems to handle new threats, such as ballistic missiles,(JASDF[Japan Air Force])

"Airspace Incursion"

JASDF constantly monitors Japan and its surrounding airspace, by national radar sites, airborne early-warning aircraft (E-2C), and airborne warning air control aircraft (E-767), for around-the-clock preparedness. When an aircraft is detected which may intrude into Japan airspace, fighters scramble to approach the aircraft, assess the situation, and take any needed action. If there is an incursion into Japan airspace, a warning to leave the airspace is issued.
"Response to New Threats"

In the event of an incoming ballistic missile, the Aegis ship of the Maritime Self-Defense Forces, radar by JASDF, Patriots (Surface-to-Air Guided Missiles), and the command and communication systems work in an integrated manner to destroy it. In the event of an armed attack by guerrillas or a special assault team, quick detection by aircraft and interception over the ocean is attempted.

http://www.mod.go.jp/asdf/en/mission/boueiryoku.html