Incontrovertibly, however, the US and Japan enjoy the only relationship on the planet whose recent baggage includes a savage war culminating in the use of nuclear weapons. Which is why the ties between these trans-Pacific pillars of global capitalism, allies of the head but not the heart, need such tending. Try telling that to most American politicians these days.
There is nothing like a Second World War anniversary to re-open old wounds. Consider Germany and the D-Day celebrations, the argument between Poland and international Jewry over Auschwitz,and compensation claims by former Far East British prisoners of war.
None though is as illuminating as the wretched saga of the Enola Gay, the B-29 bomber which dropped the atomic bomb on Hiroshima. Quite naturally, the Smithsonian Air and Space Museum decided to stage a special exhibit later this year to mark the 50th anniversary of an event which is a watershed of history. And so it set about preparing a show - not just physical exhibits (the Enola Gay's original fuselage, minutely restored for the occasion, and old footage of the events leading up to and on 6 August 1945) - but a copious explanatory text as well. American museums do such presentation better than anyone. This time, it was an unmitigated disaster.
In part, the trouble was of the Smithsonian's making. The initial text's omission of Japan's aggressions in the Far East, its portrayal of kamikaze pilots as heroic and innocent youth, and its clearly implied judgement that using the A-bomb was wrong, were not likely to win friends. Veterans' associations and conservatives were outraged, and America's most prestigious museum was accused of allowing itself to become the latest victim of political correctness. The text was rewritten. After a number of versions, a compromise seemed to be at hand. But then came the Republican takeover of Congress, and a last, fatal argument, about the number of American lives that would otherwise have been lost in a land invasion of Japan.
Historians have always believed that President Harry Truman did not hesitate to use the terrible new weapon because he believed it might save up to a million American casualties, but last month, the museum changed the draft yet again, claiming it had discovered "authoritative" evidence that military planners had predicted casualties of only 63,000 - half the number of those killed, injured or missing at Hiroshima (not to mention Nagasaki). The House Speaker, Newt Gingrich, was frothing at the mouth at this historical revisionism, while 81 Congressmen, including 13 Democrats, demanded the sacking of the museum's director.
Faced with such firepower, the Smithsonian has hoisted the white flag. The director stays, but the exhibit to all intents and purposes goes, reduced to merely the Enola Gay fuselage and a video of the crew. But future visitors need not be deterred. This will be an exhibit "every American and frankly every citizen of the planet will be proud of", says Mr Gingrich - ignoring how little America has to boast of in its recent contributions to the healing of history's wounds.
Politely and wisely, Tokyo has kept quiet on the Enola Gay fracas. But not so on the astounding plan by the US Post Office to issue a stamp depicting an atomic mushroom cloud next summer, over a caption "Atomic bombs hasten war's end, August 1945" implying that their use was justified.
After a protest by the Japanese foreign minister, the White House itself intervened to have the stamp scrapped. So honours are even, surely: American sensibilities win out at the Smithsonian, Japanese objections prevail in the case of the stamp. So I thought, before a small news item caught my eye.
A couple of years ago, a Japanese exchange student called Yoshihiro Hattori was shot dead by a homeowner in Baton Rouge, Louisiana, after being mistaken for an intruder when he asked directions for a Hallowe'en party. The tragedy caused outrage in Japan.
Here, the local authorities wanted to install a small plaque with Mr Hattori's name. But they reckoned without the memories of Pearl Harbor and the Pacific War. After much protest from veterans and others, the plan was dropped. And where does that leave "the most important bilateral relationship in the world"?Reuse content