The United States plans to conduct its first flight test for a component for an interceptor missile with Japan in the fiscal year to September 2005, defense sources said Saturday.

The plan indicates strong U.S. hopes that Japan will go beyond the research stage and actually get involved in the development of a system to protect Japan -- as well as U.S. forces based here -- from missile attacks.

Under the memorandum of understanding, originally signed in 1999 and revised in 2001, the two countries are carrying out joint research on four primary components of interceptor missiles for the envisaged defense system, which will utilize Aegis-equipped destroyers.

The four components are an infrared sensor, propulsion equipment for the second part of the three-stage interceptor missile, a warhead to hit and destroy targets and a nose cone to protect the sensor and warhead.

The U.S. is hoping to conduct joint flight tests with Japan for the nose cone over the Pacific around Hawaii for about two years, the sources said.

Japan has yet to agree to conduct nose cone flight tests with the U.S. The two countries are expected to sign a new memorandum of understanding on the missile research, including the flight tests, as early as this fall.

Based on the results of the research, Japan will decide on whether it should advance to the development stage for the eventual deployment of the system.

Flight and interception tests for the major components other than the nose cone will be conducted if the two countries shift to the development stage, the sources said.