Simon Partner is a professor of Japanese history at Duke University.
The killing of two of its citizens in the space of a week has highlighted Japan's inability to respond independently in the global "war against terror." While these acts have outraged its citizens and may strengthen calls for a stronger military stance, Japan finds itself hamstrung by the legacies of its post-Second World War settlement.
And much as the Japanese would like to think they have played only a humanitarian role in the disastrous Middle Eastern conflicts of the past decade, the truth is that Japan is deeply implicated in the struggle.
Japan's 1947 constitution "forever" renounced war, stating that "land, sea, and air forces, as well as other war potential, will never be maintained." During the succeeding decades, Japanese governments have been able to interpret this clause to further their own interests. In order to protect Japan's regional interests and ensure domestic security, Japan has built up a substantial "self-defence force" that is ranked among the world's top 10 in military power. But the constitutional ban has also allowed Japan to avoid direct involvement in a variety of dangerous conflicts, including the Vietnam War, the 1990 Gulf War, the 2001 invasion of Afghanistan and the 2003 invasion of Iraq.
Meanwhile, U.S.-Japan security treaties in force since 1951 guarantee Japan's defence against foreign invasion, albeit at the cost of hosting tens of thousands of American troops on Japanese soil.
These arrangements have served Japan well during six decades of economic and social development, but they have not been without costs. As a result of its security dependence on the United States, Japan has been a sometimes unwilling participant in America's foreign conflicts, even when they appeared to contradict Japanese interests. For example, Japan had to wait until 1972 to establish diplomatic relations with Communist China, even though peaceful relations and expanded trade with China were strongly in Japan's interest.
More recently, Japan was a major financial contributor to the 1990 Gulf War, and it was a firm though discreet ally in the 2003 Iraq War, sending troops to participate in the reconstruction effort.
Japan tries mightily to project a global image as a peaceful nation, but the truth is that so long as the security treaties are in force, it is bound inextricably to American foreign policy. Last month, at a speech in Cairo, Prime Minister Shinzo Abe pledged $200-million in humanitarian aid for countries battling the Islamic State. It was no coincidence that IS demanded the same amount as ransom money for the release of the hostages.
The Abe administration has frequently stated its desire to revise Japan's constitution to give the country greater foreign policy independence and military flexibility. The background to this is Japan's growing concern over China, which has been flexing its muscles in a variety of territorial disputes in the region.
But the current crisis also highlights Japan's relative impotence when it comes to asserting its global interests. Under the present constitution, there is little flexibility for Japan to send troops overseas to intervene in local conflicts or avenge the deaths of Japanese citizens.
In the short term, the current crisis is unlikely to result in significant changes in foreign policy. Japan's interests remain aligned with those of America, and discreet co-operation with the anti-IS alliance is likely to be Japan's best means of redress and – perhaps – revenge.
But if American and Japanese interests ever diverged to the point where the Japanese people united behind constitutional revision and a stronger military stance, Japan would quickly find itself limited in what it can do in the volatile East Asian region. China, which regards the bitter conflict of the Second World War as in many ways unresolved, would never tolerate further Japanese militarization. And a withdrawal of the American security umbrella would only underline Japan's weakness on the global stage.