Japan and the United States agreed Friday on what roles authorities of the two countries would play if an accident involving U.S. military aircraft occurred in Japan.

Guidelines approved by the Japan-U.S. Joint Committee aim to increase Japan's involvement in preserving evidence at accident sites involving U.S. military aircraft.

Protests mounted in Japan after U.S. forces did not allow police and Foreign Ministry officials to inspect an accident site in the wake of a U.S. Marine Corps helicopter crash near Okinawa's Futenma Air Station in August.

According to the guidelines, Japan will set up an "outer cordon" to restrict passersby from entering a crash site and to control traffic while the two countries jointly set up an immediate "inner cordon."

If an accident occurs, Japan and the U.S. will share information about any dangerous cargo, ammunition or fuel that might be a factor in rescue operations and for ensuring safety in the area.

Japan and the U.S. will decide who can enter the restricted site, it said.

But the guidelines did not stipulate whether Japanese authorities will be able to conduct an accident investigation. A Japanese official said the two sides will continue discussing this matter.

In August, the U.S. military rejected requests from local police to conduct an on-site investigation immediately after the crash, prompting criticism from the public. The investigation was granted after the helicopter wreckage was removed -- six days after the accident.

Foreign Minister Nobutaka Machimura told a news conference that the U.S. would need to launch the initial investigation when military secrets are involved.

The CH-53D helicopter crashed Aug. 13 on Okinawa International University campus, injuring its three crew members.