The law stipulates that the use and development of space be carried out in ways that contribute to the security of Japan, relaxing the principle of nonmilitary use based on a parliamentary resolution in 1969 under the war-renouncing Constitution.

The bill for the law cleared the House of Councillors at a plenary session, which meant its enactment as the House of Representatives passed the measure earlier this month.

Prime Minister Yasuo Fukuda's dominant Liberal Democratic Party, its coalition ally New Komeito party and the main opposition Democratic Party of Japan backed the bill, while the opposition Social Democratic Party and Japanese Communist Party voted against it.

The law changes Japan's policy of space use to "nonaggression" from "nonmilitary" and allows the government to station equipment in space compatible with the defense-oriented policy, experts and government officials said.

The equipment includes early warning satellites that can detect signs of a ballistic missile launch and a spy satellite that can view objects as small as 15 centimeters, they said.

Japan has already launched four satellites to gather intelligence on Earth since 2003 following North Korea's launch in 1998 of a ballistic missile part of which flew over Japan.

But the ability of the satellites are limited to spotting objects as small as 1 meter at maximum, a level compatible for commercial use, for fear that having one with a higher performance could draw criticism that Japan was trying to expand its military capability in space.