WASHINGTON, April 29 (Xinhua) -- U.S. Defense Secretary Chuck Hagel on Monday met at the Pentagon with his Japanese counterpart Itsunori Onodera, discussing issues of regional security, including the Democratic People's Republic of Korea (DPRK) and the Diaoyu Islands, which are China's inherent territories.

At a news briefing after the two defense chiefs meet, Hagel said they agreed that "continued close coordination" between the two countries will be essential for monitoring and responding to " any further provocations" of the DPRK, particularly on missile defense," and they "made progress on plans to deploy a second TPY- 2 radar to Japan."

Hagel said the two also discussed "ongoing friction in the East China Sea," saying the United States "does not take a position on the ultimate sovereignty of the islands," but consider the Diaoyu Islands are "under the administration of Japan and fall under our security treaty obligations."

"Any actions that could raise tensions or lead to miscalculations affect the stability of the entire region," said Hagel.

China has repeatedly protested to Japan over its illegal navigation in waters around the Diaoyu Islands.