Defense Minister Itsunori Onodera on Monday urged the United States to work to reduce the concentration of military bases on Okinawa when he met with the U.S. military's top commander in the Pacific.

"Okinawa approved our permit (for landfill to relocate a military base) in late December, and we'd like to ask the U.S. side for more steps to mitigate the impact on Okinawa," Onodera told Adm. Samuel Locklear, commander of the Pacific Command, at the Defense Ministry.

Also on Monday, the city assembly of Nago, where the operations of U.S. Marine Corps Air Station Futenma in Ginowan are to be relocated once the new airstrip is completed, adopted a document demanding Okinawa Gov. Hirokazu Nakaima retract his approval for the fill work to start for offshore sections of the new base. The Futenma relocation, first agreed upon between Tokyo and Washington in 1996, has met strong opposition in Okinawa.

Onodera and Locklear discussed moving some training exercises conducted by the U.S. Marines' MV-22 Osprey aircraft from Okinawa, according to the Defense Ministry.

The meeting came before Japan and U.S. officials held their first working-level talks on how to counter cyber-attacks, often blamed on China and North Korea.

"The stable use of cyberspace is an important bilateral security issue, and we want to cooperate with the United States," Onodera said.

Amid North Korea's missile and nuclear threats and an assertive China, Prime Minister Shinzo Abe is trying to bolster the capabilities of the Self-Defense Forces and strengthen the Japan-U.S. security alliance.