Japanese authorities were shocked on Wednesday by the Democratic People's Republic of Korea's satellite launch, despite the fact that there was no damage and no debris fell on Japan.

Observers were concerned that more radical voices may overreact to Pyongyang's rocket launch during Japan's election campaign and influence a new government's hard-line defense policies.

Republic of Korea conservative activists set fire to a mock Democratic People's Republic of Korea missile during a protest denouncing Pyongyang's rocket launch in Seoul on Wednesday. [Photo/Agencies]

Japan's Chief Cabinet Secretary Osamu Fujiwara, speaking at a hastily called news conference at the Japanese prime minister's office, said: "The act is unacceptable, and we will lodge a strong protest against Pyongyang."

Tokyo said the "missile" passed over its southern island chain of Okinawa after takeoff.

Japanese Prime Minister Yoshihiko Noda convened the Security Council of Japan at 10:50 am to discuss the government's response to the launch.

Japanese Defense Minister Satoshi Morimoto told reporters on Wednesday afternoon that the DPRK has made advances in its rocket launches.

Zang Zhijun, a professor of Japanese studies at Fudan University in Shanghai, said most of the ruling cabinet's previous sensational moves threatening to target the launch were a "posture" to show toughness.

"The United Nations Security Council did not entitle Japan to shoot down the rocket or its debris, and Tokyo seems not to have made enough preparations for a possible successful liftoff," Zang said.

The liftoff occurred just four days before Japan's House of Representatives election. Main political parties condemned the DPRK for launching the rocket.

Jun Azumi, acting secretary-general of the ruling Democratic Party of Japan, said the DPRK's act cannot be tolerated.

Japan's main opposition party, the Liberal Democratic Party led by former prime minister Shinzo Abe, said in a statement that the launch damaged peace and stability in the East Asian region and is a challenge to the international community.

Although the launch may not have a major impact on the election result, the overall atmosphere will be heated up by Pyongyang's rocket launch, Zang said.

"The so-called danger, which has been played up as 'mounting', will provide a good excuse for right-wing politicians to call for military expansion and a review of the 'peace constitution,'" Zang warned.

The sudden liftoff raises questions about the intelligence-gathering capabilities of Japan, the United States and the Republic of Korea.

Shortly after the launch, Tokyo asked the UN to convene an emergency meeting of the Security Council.

Japan alleged that the DPRK's satellite launch is a covert test of long-range missile technology in violation of UN Security Council resolutions.

Tokyo has constantly exaggerated some of Pyongyang's moves for its own "political intentions", said Shi Yongming, a researcher of Asia-Pacific studies at the China Institute of International Relations.

"It tries to convince the general public that 'we are under threat' and the 'peace constitution' has not been good for the country's security. It claims the DPRK is a source of the threats," Shi said.

Japan's Self-Defense Force completed the deployment of troops to intercept the satellite on Sunday, eight days after Pyongyang announced plans for the launch.

The SDF dispatched three Aegis-equipped destroyers with SM3 missiles to the Sea of Japan and other maritime areas, including the Sakishima Islands in Okinawa Prefecture.

They also deployed surface-to-air Patriot Advanced Capability-3 missiles to seven locations, including Ishigakijima Island and the prefecture's main island, as well as the Tokyo metropolitan area.

The SDF also prepared for the possibility that toxic fuel residue from the rocket launch could fall on Japanese territory. Chemical warfare vehicles and gas masks were sent in to deal with that contingency.

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