Aug 15 was Victory over Japan Day. In 1947, two years after Japan surrendered, ending World War II, it adopted a new constitution drafted largely by US lawyers.

Sixty-five years on, a former high-ranking US government official is calling a particular article of the constitution an impediment to the alliance between the US and Japan.

Referring to Article 9 of Japan's "Peace Constitution", which prohibits an act of war by the state and bans use of force to settle international disputes, former US deputy secretary of state Richard Armitage said: "We ... describe this as an impediment to our alliance cooperation. I don't think one can argue that fact."

Armitage's remarks - made on Wednesday at the Center for Strategic and International Studies in Washington, in conjunction with the release of his report, The US-Japan Alliance: Anchoring Stability in Asia - reflect an attempt by the US to allow Japan to play a role in the US' "return to Asia" strategy, Chinese analysts said.

Feng Zhaokui, a Japanese studies researcher with the Chinese Academy of Social Sciences, said Japan has been trying to loosen the grip on its military policies, and many of its recent moves have shown signs of "going beyond the constraint" of Article 9.

Washington is shifting its strategic emphasis and pivoting to Asia, and it needs its allies in the region to share the burden because of its tightened defense budget, Feng said.

But in the eyes of those who tout a bigger military role of Japan to supplement the US' Asia-Pacific strategy, "Article 9 has prevented Japan from implementing collective self-defense, and it serves as a stumbling block for Japan to fully function to correspond with US global strategies", Feng said.

Armitage also suggested "a responsible authorization" on Tokyo's part to allow the US military and Japan Self-Defense Forces "to respond in full cooperation throughout the security spectrum of peacetime, tension, crisis and war".

Robin Sakoda, a partner at the former US official's consulting firm, Armitage International, and a researcher on the report, said the goal of closer US-Japanese cooperation would be advanced by removing constraints now.

"We are not seeking to change (Japan's) constitution," Sakoda said. "We are not seeking unified command. We are not seeking for Japan to become more militaristic in character. The aim is that we need to get rid of the impediment so our forces can work together more efficiently and effectively."