Japan's Defense Minister Takeshi Iwaya has said it is still possible for North Korea to launch more missiles, and vowed to strengthen surveillance activities.
Iwaya made the remark on Thursday as Pyongyang has repeatedly fired what appear to be short-range ballistic missiles in recent weeks.
The minister said North Korean media say the launches were made to protest against US-South Korea joint military drills.
Since the drills will continue through next Tuesday, Iwaya said his ministry will keep a close watch on the situation.
He also expressed hope that Japan's intelligence-sharing pact with South Korea, known as GSOMIA, will be extended.
The pact is automatically renewed every year, but either side can pull out by giving notice by August 24.
Iwaya said Japan-South Korea diplomatic relations have soured, but the two countries face the common challenge of dealing with North Korea's nuclear and missile programs.
He said that amid such a situation, GSOMIA is a very important framework to facilitate intelligence-sharing between the defense authorities of Japan and South Korea.