This is the first instalment of a series that focuses on the Japan security environment.
Senior officers of the US Navy Seventh Fleet visited the Self-Defence Fleet headquarters of the Maritime Self-Defence Force in Yokosuka, Kanagawa Prefecture, this summer to join an MSDF tactical simulation.
It was based on a scenario in which Japan and the United States would work together to deal with an emergency involving the Senkaku Islands in Okinawa Prefecture.
In the scenario, a large number of ships that appear to be Chinese fishing boats sail to the islands. Men posing as fishermen then go ashore on the islands.
The Japanese and US officers confirmed through the simulation how and under what rules of engagement they would deploy their troops to deal with such an emergency and prevent it from escalating into an armed conflict.
It was the first time the US Navy directly joined an MSDF tactical simulation.
"The United States has finally become serious about situations regarding the Senkakus," said an MSDF senior officer who apparently felt a subtle change in the attitude of the US forces.
An MSDF destroyer is scheduled to accompany a US aircraft carrier on a long-term cruise this autumn for navigational training purposes. Last year, an MSDF destroyer joined a US fleet with an aircraft carrier at its centre.
Now that the security laws have been enacted, the meaning of the MSDF's participation in such operations has changed.
With the enforcement of the security laws, the Self-Defence Forces and the US forces can defend each other's vessels by using weapons during joint exercises, and by undertaking warning and surveillance activities.
In a "situation threatening Japan's survival," it is assumed that MSDF ships would defend a US aircraft carrier based on the right of collective self-defence.
Prime Minister Shinzo Abe has told his aides that the significance of the security laws is to enable the MSDF to conduct integrated operations with the US Seventh Fleet.
The joint navigation in autumn is expected to be a training exercise in preparation for future Japan-US integrated operations.
When SDF Chief of Joint Staff Adm. Katsutoshi Kawano visited Washington in the middle of July, shortly before the security bills were passed in the House of Representatives, US Vice President Joe Biden greeted him.
Biden expressed concern over the security environment in East Asia, including China and North Korea, and told Kawano that he had taken an interest in Japan's security legislation.
It is quite unusual for a US vice president to meet a uniformed leader of an armed force of a foreign country.
"A US vice president has never been so talkative during a meeting with an important figure from Japan," said an official of the Japanese Embassy in Washington.
The talks gave Japan the impression that the United States placed great importance on the Japan-US alliance.
Former head of the SDF's Joint Staff Adm. Takashi Saito talked about the relationship between the SDF and the US military after the enactment of the security laws.
"The United States will help Japan defend its remote islands, and we will help the United States by exercising the right of collective self-defence, which is a well-balanced [relationship]," he said.
While the United States makes every effort to simultaneously reduce military spending and maintain its presence, Japan wants to strengthen its deterrent capacity by shouldering part of the US burden.
The security laws satisfy the interests of the two countries.
Japan answers US calls for co-operation
In August 2012, then Defence Minister Satoshi Morimoto held talks with his US counterpart, then Defence Secretary Leon Panetta, at the Defence Department in the suburbs of Washington, D.C. At the meeting, Morimoto proposed a study of possible revisions to the Guidelines for Japan-US Defence Cooperation - a set of guiding principles about the roles to be assumed by the Self-Defence Forces and US forces.
"China, North Korea and Russia have changed. There are also talks in the United States about rebalancing," Morimoto was quoted as telling Panetta. "The security environment surrounding the guidelines is undergoing great changes."
The Japanese and US defence chiefs arrived at a consensus about the changing security environment. In November that year, then Senior Defence Minister Akihisa Nagashima visited the United States, where he reached an agreement with then US Deputy Defence Secretary Ashton Carter to make progress in carrying out the proposed study.
But according to Morimoto, the United States told Japan that the study wouldn't result in a true review of the guidelines if there was no change in what Japan would do despite the changing security situation.
Ultimately, the Japan-US agreement reached under the administration led by the Democratic Party of Japan produced nothing more than some research on the review.
What prompted Washington to take action was the new security-related legislation drafted by the Cabinet of Prime Minister Shinzo Abe, which sufficiently answered US calls made over the years for bilateral defence co-operation. Washington's requests to Tokyo included lifting Japan's self-imposed ban on its right of collective self-defence and permitting itself to exercise that right to a limited degree.
The United States had also urged Japan to expand its so-called rear-echelon assistance, or logistic support, and end restrictions on its geographical scope.
The review of the guidelines started immediately after the launch of Abe's second Cabinet. Some changes were finalized in April, including "the defence of islands" in an apparent nod to the Senkaku Islands. US President Barack Obama himself had clearly stated that US obligations to defend Japan included the Senkakus, as stated in Article 5 of the Japan-US Security Treaty.
These developments are by no means an indication, however, that Japan and the United States are on the same page over guideline revisions.
For one thing, the new guidelines state that the two countries will "plan" and "update" joint operations, but sources say US forces remain reluctant about drafting a joint operation plan related to the Senkakus.
"The United States seems to feel that drafting an operation plan for a possible military contingency could provoke China," a senior SDF official said.
Abe has already denied the possibility of extending SDF logistic support for the ongoing campaign to uproot the Islamic State of Iraq and the Levant (ISIL) militant group, despite expectations persistently expressed by some circles within the United States about such SDF assistance based on the new security legislation.
"I'm not thinking about providing rear-echelon support for [clean-up] operations at all," Abe has said in response to a question at a Diet session and on other occasions.
The commander of the US Pacific Command reportedly said earlier on that he would "welcome" SDF patrols in the South China Sea, where China has been stepping up maritime activities.
Defence Minister Gen Nakatani, who is also minister for security legislation, described SDF activities of that kind as just "a matter for consideration."
The Defence Ministry must allay the "excessive expectations" held by the United States, a ministry official said. "The United States is mistaken to think Japan will come to its aid whenever it is attacked."
An important question is the appropriate extent to which Japan and the United States should deepen their defence co-operation, with the possible scope of such a cooperative relationship now expanded through the new security-related legislation and the revised guidelines.
The way things stand, the two nations seem to be heading toward a tug-of-war over their own motives regarding bilateral defence co-operation.