For a seven-year period that lasted from the signing of the Potsdam Declaration on August 15th 1945 to the date when the Peace Treaty came into effect on April 28th 1952, for the first time in its history, Japan found itself occupied by a foreign military force. Though officially carried out by the Occupation Council for Japan, which involved the United States, the USSR, China and Australia (on behalf of Britain), it was the first of these nations that soon came to dictate the direction in which the occupation was led. Thus the period came to be known as "The American Occupation".

Her own colonial intentions brought to a rapid halt with the dropping of the atomic bombs on the cities of Hiroshima and Nagasaki, Japan now found its fortunes steered from Washington, a seat of power with a rather different view of Japan's future role in world affairs than that of its own militarist government that had steered the country into war with the rest of the world. The occupation would naturally have a profound effect on the Japanese psyche, and naturally, as a result, on the nation's culture. How much this stemmed naturally from the Japanese themselves and how much this was influenced by the foreign agencies involved in the nation's reconstruction is one of the key areas that the book Mr Smith Goes to Tokyo attempts to shed light on.

In the days before television, with few other sources of entertainment left open to a defeated populace, the primary means of disseminating ideas and ideals across the nation was via the cinema screen. In comparison to other countries in Asia, Japan had a strong and firmly established legacy of film production and distribution, and one that was put to service by the wartime government in producing various types of propaganda: culture films (bunka eiga, documentary works that promoted various aspects of Japanese life and culture); wartime newsreels (jiji eiga, or "current films"); jingoistic entertainment features whose narratives served as rousing calls to arms, such as Fire on that Flag (Ano Hata O Ute, 1944) or The All-Out Attack on Singapore (Shingaporu Sokogeki); and sinister cartoon entertainment for kids such as Momotaro, Eagle of the Sea (Momotaro no Kaishu, 1942).

One of the goals of the new occupation government was to bring Japanese cinema in line with its own policies. This meant a purging of those traits from its cinema that had fostered the cultural environment that made it easier for the militarists in power to lead the country into war, traits such as narratives focused around feudal loyalty and the glorification of military heroes from the past. In its place, through the medium the Americans stressed the promotion of "democratic values" such as individuality, and freedom of expression.

Published in 1992, Kyoko Hirano's scholarly yet accessible look at Japanese film under the conditions of the occupation has been out for some time now, but given that it is the only detailed book on the subject, it still remains as crucial a read as ever. Written at a time when official documents from both Tokyo and Washington had just become declassified, it looks back at the events it writes about from a distant enough viewpoint to avoid the kind of emotively-fuelled pontificating that marred, for example, Siegfried Kracauer's From Caligari to Hitler: A Psychological History of the German Film, published only two years after the war in 1947.

The opening chapters illuminatingly detail the background to the occupation before moving on to Hirano's central theme: the effect that it had on the cinema of this period. During this time, a double censorship system existed in which scripts first had to be translated into English by the film companies before being vetted by the Civil Information and Education Service (CIE), coming under scrutiny one further time once the film had been completed.

Hirano manages to pinpoint several ironies of this transition period between Japan's return to self-rule, but perhaps it is best to state at this point that occupation censorship was certainly a lot more lenient than that of Japan's wartime government, which in its later stages had prohibited the use of foreign words, films portraying the lives of rich people, films dealing with sexual frivolity, and films showing the adoption of foreign customs, amongst other things.

This nevertheless resulted in a form of propaganda that was subtle, highly dramatic and hence very effective, and surprisingly rarely plumbed the racist depths of the worst US examples of the time, which demonised their enemies as monkeys or vermin. Instead Japanese propaganda glorified indigenous traditions and the nation's long cultural history, untarnished by outside influence for so long, and how these things were being threatened by the looming shadows of the colonial nations gathering throughout the rest of Asia. They promoted a standardised morality, a shared sense of common culture, an austere lifestyle and an unwavering dedication to the war effort.

When the occupiers arrived, 236 such films made between 1931 and 1945 were deemed as "ultra-nationalistic", "militaristic" or as "propagating feudalism", and all existing copies rounded up and destroyed. Fortunately the negative and four prints of all of these films were sent to the Library of Congress in Washington D.C. to be later returned to Tokyo's National Film Centre in 1967.

The greatest anomaly though is that the filmmakers responsible for these films were the same ones who continued to make films during the occupation period. No film director was ever convicted of war crimes for their involvement in making these works of propaganda, and even though numerous film industry leaders, heads of studios and producers were all removed from their posts after Japan's defeat, many were reinstated to their former posts before the end of the occupation (one notable example was Shochiku head Shiro Kido). For many directors, the occupation period just meant continuing to make films under radically different guidelines and working conditions, resulting in such well-known cases as that of Akira Kurosawa's The Men Who Tread on the Tiger's Tail (Tora no O o Fumu Otokotachi, 1945), which, being completed in the year straddling the two orders, found itself banned by both the Japanese and the American authorities.

Of course, it is always amusing reading about the more outrageous examples in any survey of censorship at a given point in a country's history, and much of the evidence assembled by Hirano makes for pretty eye-opening stuff. In attempting to repress supposedly atavistic military tendencies in Japanese film, the US occupiers tried to stamp out subjects glorifying feudal tendencies and based on famous historical military figures. This in reality meant an almost blanket ban on any period dramas, including all adaptations of Kabuki plays. In fact, even public performances of Kabuki in its stage form were strictly prohibited initially. The usage of swords, the traditional weapon of choice in Japan, was also banned from the screen, and Mount Fuji, which had been attributed an almost mythological status as an emblem of Japan during the war and its immediate run-up, was also a no-go area.

On the other hand, Japanese filmmakers were wholeheartedly encouraged to make "democratization enlightenment films", espousing the mores and values of the new world. According to Hirano, Japanese audiences were more or less "force-fed American ideas". As the occupation encouraged production around the three S's - sex, screens and sport - there was a rash of "baseball movies", to re-popularise a sport that had been banned by the government during the wartime period.

Female emancipation was one particular area they wished to foster, and one rather unusual by-product of this was the rise of the "kissing film". Fearing that the lack of affection displayed by the Japanese in the public sphere was symptomatic of their furtiveness, the US actively encouraged kissing scenes during the late-40s. Their popularity soon gave rise to newer, bolder forms of sexual expression, in the form of the first public striptease in 1947, and the birth of the kasutori zasshi, or "dregs magazines", cheaply-produced examples of early Japanese pornography.

But the greatest irony was that the occupation censorship was so fundamentally compromised by the very values it was trying to put forward. It could never be known to the general Japanese public that those who promoted freedom of expression on the one hand were also pre-censoring scripts behind the scenes. Despite the large role they played in everyday life, as far as cinema went, the occupation had to remain virtually invisible: the one thing that the modern-day viewer notices about the films of this period is that the occupier is never alluded to. There are no signs of soldiers; no English-language signs; no US planes flying over head; films about mixed-blood offspring of the locals and American soldiers were never produced; indeed no foreign faces at all are in evidence. Hirano cites the surprise of Joseph L. Anderson, co-writer with Donald Richie of The Japanese Film: Art and Industry, on seeing Hiroshi Shimizu's Children of the Beehive (1948), who wondered how so many scenes in the film could have been shot around train stations, which at the time were heavily sequestered by the US military.

Within the seven-year occupation period, Hirano notices a decisive split in the occupational policy towards Japan, a split which is not only represented within the films and film censorship practices, but also in events that took place around the industry, such as a series of strikes held by the creative elements at Toho Studios during the late 1940s. In the early years, she notes that the occupation's goal was purely idealistic, a genuine attempt at bringing Japan into line with the rest of the world and making her a peaceful country once more - "the Switzerland of Asia," as Supreme Commander, Allied Powers (SCAP) General Douglas MacArthur put it.

But towards the end of the 40s, as the Cold War escalated between the USA and the USSR, another agenda soon began to take hold, which was to recruit Japan as an ally against communism. The Communist Party in Japan had suffered mercilessly from state persecution during the war, its ideals being based on "alien" ideas that threatened to pollute the idea of kokutai, the Japanese national body. At the end of the war, having opposed Japan's right-wing military government, the communists enjoyed a great deal of public sympathy. It was a sympathy that was not shared by their new rulers, however. Once the occupation was over, under the newly appointed Japanese government, communists in Japan once more found themselves out of favour, leading to many left-leaning figures being purged from public positions, as was the case in America around the same time.

A full 460,000 American soldiers were stationed in Japan in 1946, and though the numbers declined over the following years to around a quarter of this figure, they soon swelled again to between 210,000 and 260,000 with the American involvement in the Korean War in the early 1950s, and stayed firmly put long past the Peace Treaty was put into effect, with the US retaining control over Okinawa all the way up until 1972. Even today around 50,000 military personnel remain on Japanese soil.

In a final chapter, entitled "The Legacy of the Occupation", Hirano asserts that Japan's "miraculous" economic growth was in no small measure due to the occupiers decision to allow the wartime zaibatsu, the industrial conglomerates who had collaborated so influentially with the militarists, to return to the scene. Despite its new constitution, written by its occupiers, dictating that Japan was never to hold its own army, by 1991 Japan had the highest military budget in the world, spent on the so-called Self-Defense Forces.

And of course the story is not over yet. In 2003, against a large backdrop of public protest, Prime Minister Junichiro Koizumi authorised the historic decision to send troops overseas to Iraq, the first time a Japanese military force had served overseas since World War 2. At a time when modern Japanese citizens are more likely to know about their own nation's history through The Last Samurai than the likes of their own indigenous and oft-filmed tale Chushingura (The Loyal Forty Seven Ronin), which manifested many of the aspects of feudalism and tradition that the occupational government had frowned on, it would appear that though the US occupation may have officially ended over 50 years ago, the country's influence over Japan's role in world affairs is far from complete.