(KUNA) -- Japan remains on alert Thursday as North Korea may launch another ballistic missile after it test-fired seven missiles Wednesday, all of which landed harmlessly in the Sea of Japan. Security at Japan's nuclear plants is tight, while the Self-Defense Forces dispatched reconnaissance planes to monitor radio contact among North Korean troops. Pyongyang launched seven missiles, including one long-range missile called the Taepodong-2, which is believed to be capable of reaching as far as the US west coast at its full capacity. "We can not rule out the possibility of further launches," Chief Cabinet Secretary Shinzo Abe told a news conference. "We are aware of media reports about a second Taepodong-2 missile and are keeping an eye on the developments, " the top government spokesman added.Defense Agency Director General Fukushiro Nukaga told parliament that the government will upgrade efforts to establish a joint anti-missile defense system with the US as soon as possible. Japan and the US began a joint missile defense research project in 1999 after North Korea stunned the world by firing a long-range Taepodong-1 missile over Japan into the Pacific Ocean.
In Seoul, South Korea's top defense official acknowledged the possibility that North Korea will test-fire more missiles, Yonhap News Agency reported. "The possibility is based on the assessment of the equipment and groups going to and from (the launch sites) during North Korea's preparations over the past two months," Defense Minister Yoon Kwang-ung told the committee.