The move comes amid a standoff over North Korea's nuclear weapons drive and six years after Pyongyang test-launched a missile over Japan.

"Under current procedures we could not respond in time after a missile is prepared and appears ready to strike Japan," Chief Cabinet Secretary Hiroyuki Hosoda told a news conference.

Hosoda said the government was still working out specific measures.

Under current procedure, the prime minister must convene his cabinet and a national security council to decide on any military action.

Kyodo News reported that Defense Agency Director-General Yoshinori Ono, on a weekend visit to Washington, said he wants to allow the prime minister to bypass the meetings in the event of a missile launch.

Japan's constitution imposed after World War II renounces war, but the ruling Liberal Democratic Party is reportedly mulling an overhaul of the document to allow a limited use of force.

Japan's military, known as the Self-Defense Forces, has asked for a 35 percent increase in missile defense and intelligence systems spending for the fiscal year to March 2006 to 144.2 billion yen (1.4 billion dollars).

The money would be used mainly to buy seaborne SM-3 missiles, upgrade land-based PAC-3 anti-missile systems and remodel high-tech Aegis system-equipped destroyers.

North Korea provoked an international outcry in 1998 by firing the missile over Japan, which the Stalinist state claimed was a satellite launch.

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