Japan and the U.S. have agreed to share data and strengthen the monitoring of space debris to avoid collisions with satellites and other objects in space, sources said Wednesday.

The agreement comes as the amount of space debris, including unused satellites and their fragments, is believed to total more than 500,000 items, the sources said. The debris poses a danger to working satellites and the safety of astronauts at the International Space Station.

Orbiting the Earth at speeds of up to 8 km per second, the space junk could hit communications, broadcasting and GPS satellites at any time.

The two countries also agreed to work together in securing ground safety by quickly detecting the landing points of retired satellites set to fall to Earth, the sources said.

Japan is considering using the Self-Defense Forces' missile radar system for these efforts, while offering data on space debris collected by radar and telescope to the U.S., they said.

Currently Washington has a leading role in tracking space debris, with the U.S. military constantly following the movements of debris 10 cm in diameter or larger, and providing the data to countries worldwide, they said.

But as the U.S. cannot precisely detect the location and movements of smaller pieces of debris, Japan will step up efforts to develop new technology to detect such pieces, they said.

Japan and the U.S. also agreed to lead international talks for rules to reduce space debris.