South Korea's chairman of of the joint chiefs of staff hosted his counterparts from the U.S. and Japan in Seoul on Friday.

The top military officer of the United States stressed the importance of security cooperation among South Korea, the U.S. and Japan to reestablish deterrence against an "unprecedented" military buildup by North Korea and China.

South Korea, Japan and the United States conducted a joint air drill on Friday involving a U.S. B-52 strategic bomber and fighter jets of the three allies over international waters, the South's defence ministry said.

Visit by General Dan Caine, top US military officer, comes amid growing calls in Washington for South Korea to shoulder more defence costs.

The top military officials of South Korea, Japanese and the United States urged North Korea on Friday to halt all unlawful activities threatening regional security as the three nations flew advanced warplanes for a joint exercise in a show of force against Pyongyang.

Against this backdrop, this article examines the challenges for U.S. allies such as NATO and Japan and how they should collectively respond to the new US approach to alliance management. The post-World War Two (WWII) world order was based on the premise that five permanent members of the United Nations Security Council would cooperate to maintain peace and stability of the world even though doing so could diminish national interests of those countries.

TOKYO (Reuters) -Japan will export used navy destroyers to the Philippines to strengthen its deterrence against China's maritime expansion, the Yomiuri newspaper reported on Sunday, as the two U.S. allies increase cooperation to counter Beijing.

The top military officer of the United States stressed the importance of security cooperation among South Korea, the U.S. and Japan to reestablish deterrence against an "unprecedented" military buildup by North Korea and China.