As concerns mount over the threat posed by North Korea, the debate over Japan introducing missile defense systems is heating up.

The Defense Agency is studying the introduction of two types of system to knock down incoming ballistic missiles. One is a sea-based system and makes use of Aegis-equipped destroyers; the other is a ground-based PAC-3 system, an advanced version of the Patriot missile defense system.

With the two proposals in mind, the agency is preparing its budget requests for fiscal 2004.