Growing foreign interest in Asian security, including North Korea's development of nuclear weapons and ballistic missiles, coincides with greater Japanese willingness to back up its regional diplomacy with a show of military muscle.
Tokyo this year sent its biggest warship, the Kaga helicopter carrier, on a two-month tour of the Indo Pacific, including flag-waving stops in the Philippines, Indonesia, Sri Lanka, India and Singapore.
The 248 metre (813.65 ft) long Maritime Self Defence Force ship and its two destroyer escorts also conducted drills with a Japanese submarine in the contested South China Sea.
At the same time, Japanese Prime Minister Shinzo Abe has engaged China in dialogue to reduce tension between their militaries in the East China Sea and to increase economic cooperation between Asia's two leading economies.
Amid a background of trade friction with Washington, Abe last month traveled to Beijing, the first such trip by a Japanese leader in seven years, for talks with President Xi Jinping and Premier Li Keqiang. Abe told them that China and Japan shared responsibility for regional security, including tackling North Korean.
Japan, however, still views China as a potentially much larger and more challenging foe than Pyongyang as its expanding navy consolidates control of the South China Sea and ventures deeper into the Western Pacific and Indian Ocean.
Beijing this year plans to spend 1.11 trillion yuan ($160 billion) on its armed forces, more than three times as much as Japan and about a third of what the U.S. pays for a military that helps defend the Japanese islands.
Keen Sword "remains an expression of the commitment of like minded allies and partners. To really see what we can do in terms of demonstrating advanced capabilities together to ensure peace and stability in the Indo Pacific," Chief of U.S. Naval Operations Admiral John Richardson said on Thursday in Australia during a telephone press briefing.
