Denouncing Tuesday's nuclear test by North Korea, the government called on the U.N. Security Council to meet and impose more severe sanctions against the hermit nation.

Chief Cabinet Secretary Yoshihide Suga said Japan lodged a protest with North Korea via its embassy in Beijing. He said Japan's delegation at the U.N. has called for holding a Security Council meeting because North Korea violated Resolution 2087, which warns that Pyongyang would face "consequences" if it conducted any more nuclear tests.

Prime Minister Shinzo Abe issued a statement saying the test poses "a serious threat to the security of our country" and "a serious challenge to the international framework for disarmament and nuclear nonproliferation."

Appearing in the Diet, he said Japan "will use every possible option, including our own sanctions, to counter the problem."

In the prepared statement, Abe said Japan will expand a ban on re-entry by top officials of the General Association of Korean Residents in Japan, the pro-Pyongyang group better known as Chongryon, if they visit North Korea. Only the people in the four top positions had been barred from re-entry, but now the five vice chairmen will also be subject to the ban.

Japan is likely to impose further financial sanctions, such as trying to completely cut off the flow of money to North Korea. This will likely have a minimum impact, however, because of China's reported financial assistance for Pyongyang.

Abe ordered officials to monitor radiation levels in various parts of the country. Two military training jets joined the effort.