The rape of a schoolgirl was the final straw. Now the Japanese are fighting back, writes Richard Lloyd Parry
In parts of Okinawa you see more English on the streets than Japanese. Everywhere you look you find it: on signs, shop fronts, T-shirts and souvenir cigarette lighters. "US Military Property - Entry Prohibited" is the commonest message, posted along the miles of fence that ring the 16 huge American bases, closely followed by peppy slogans such as the one by the gate to the Marine Corps' Camp Foster: "Military courtesy is infectious - catch it!"

Nearby, in the town of Koza, are streets of gift shops catering to the 52,000 military personnel and their families: "Smoke Dope, Drink Beer, Eat Pussy" reads the motto on one novelty baseball cap. But the slogan of the moment is round the corner, drunkenly scrawled on the door of Champ, a disco favoured by GIs. "I Love 11-year-olds," somebody has written in black felt-tip: "In Leather Underwear!!"

Even by the standards of military humour, it is an exceptionally sick and ill-timed joke. Tomorrow evening, in a field near the Camp Butler marine base, a huge rally will be held to protest at the presence of the American military. The organisers expect a crowd of 50,000 people; it will be the biggest demonstration since 1956, when Okinawa was still an American territory, governed by a US general.

The focus of the demonstration is referred to by Okinawans as reipu jiken - "the rape incident", using the Japanese pronunciation of the English word. On 4 September, an Okinawan child was gang-raped by three US servicemen. In six remarkable weeks, a small local tragedy has mushroomed into a major diplomatic incident, the biggest threat to Japanese-American relations in 25 years.

The victim was 12, not 11, and far from being clad in leather, she was wearing her school uniform. Late in the evening, she was walking through her home village, carrying student exercise books that she had bought in a local shop. On her way home she passed a white car, hired from a military rental firm on a Marines base. In it were Kendrick M Ledet and Rodrico Hart, Marine privates, and a Naval Seaman, Marcus D Gill. They were waiting for an Okinawan woman, any woman.

Today, the men are in an Okinawan jail. Their trial begins in three weeks, but even their officers concede that the crime was planned from the beginning. They told several of their colleagues what they were planning to do, and spent the day driving around the island and shopping. Among their purchases was a roll of adhesive tape. It was 8 o'clock when the girl passed by.They bundled her into the back, taped her mouth, and drove to a nearby field overlooking the sea, where they raped her.

It was an astonishingly naive and bungled crime. The victim staggered home and was taken by her family to the police station the same night. The discarded gag was quickly found, along with the bag of new exercise books. The hire car was traced the next day, as was another serviceman whom the three had tried to enlist earlier in the day. "It almost makes it more arrogant, more insulting that they made no attempt to cover their tracks," says one old Okinawan, "almost as if they had a right to this girl."

In Okinawa, the uproar was immediate, but it quickly went beyond the predictable outrage at the violation of an innocent. In its nature and its timing, it has begun to look more and more like a horribly appropriate crime, almost an emblem of Okinawa itself.

For centuries, the Ryukyu Islands, as the Okinawan archipelago used to be known, were independent, an idyllic subtropical kingdom with its own unique language, music and literature, and a prosperous trade with China and Japan. Since the 15th century, though, the "Isles of Courtesy" have been batted around between expansionist powers. First, the Chinese demanded vassalage; then, in the 17th century, Okinawa was forced to pay tribute to the lords of Japan, of which it became an administrative unit in 1878. In 1945, it was the only part of the mother country to suffer a land battle between the American and Japanese forces: a third of the civilian population, 120,000 people, died.

Since then, it has suffered the burden of the American bases, which take up a fifth of the land area of the main island. Until 1972, when the US handed the reins of government back to Japan, they took up even more. In parts of Okinawa, schoolchildren have to cover their ears as the fighters come in to land at the airfields next to their playgrounds. Hillsides in the north are denuded by artillery firing.

The Americans are at pains to point out that the number of offences committed by military personnel has declined steadily since the 1972 reversion to Japan - none the less, over the 23 years, 4,716 offences have been pinned on the armed forces, including a dozen murders. There have been rapes, too, although accurate numbers are far harder to determine. The Marines acknowledge that many accusations of sexual assault never make it to court.

"Incidents like this happen regularly," says Teruko Kuwae of the Okinawa City Women's Policy Promotion Centre. "Women who suffer this kind of thing, especially in Japan, don't want everyone to know about it."

But one notorious incident is constantly cited by people in Okinawa, and with good reason. During the American Occupation, a six-year-old girl called Yumiko was raped and murdered by a 31-year-old Marine, who threw her body into the sea. It happened on 4 September 1955, 40 years to the day before last month's child rape.

In June, the 50th anniversary of the battle for Okinawa was marked by a subtle tension between the US military and the Okinawan civilian authorities. While the Okinawans mourned the devastation of their island, the Americans - including hundreds of elderly veterans flown in for the occasion - celebrated a great and costly victory. The two sides rarely met. On more than one occasion, plaques erected by the Americans proved too gung-ho for Okinawan tastes, and had to be withdrawn or toned down.

Okinawan politics has taken a radical turn recently, under the stewardship of its present governor, Masahide Ota, who witnessed the wartime devastation as a teenager. By area, the islands make up just over half a per cent of Japan, but three-quarters of all US bases in Japan are concentrated here. Some 80 per cent of Okinawans want this proportion to be reduced or eliminated. But in the 23 years since reversion to Japanese rule, little more than 15 per cent of occupied land has been handed back. Ota, the first governor to be elected in the post-Cold War period, has set himself the job of rectifying this imbalance.

The task is a formidable one, pitting little Okinawa against not just one, but two national governments. US bases all over the country are maintained under the controversial US-Japan Security Treaty, or Ampo, as it is known in Japan. Both governments get a very good deal out of it. In return for the guaranteed protection of the United States, including its nuclear umbrella, Japan pays for the rent and upkeep of its bases to the tune of $5bn a year. Bizarrely, it is cheaper to maintain American troops in Japan than in the United States.

On paper at least, the Okinawan bases are there because the Japanese government wants them there. But, as a local academic points out, "We, the Okinawans, are stuck in this bilateral sandwich. If Ota complains to the Americans, they say it's Tokyo's problem. When he goes to Tokyo, they shake their heads, and suck their teeth and say they sympathise, but that because of Ampo it's chotto muri ...." Chotto muri is a very Japanese expression, popular with politicians in a tight spot. It means "somewhat completely impossible".

The somewhat completely impossible position has been maintained for 23 years. Under the Security Treaty, any bases removed from Okinawa must be relocated somewhere else in Japan. Nobody, least of all politicians in Tokyo, wants the Marines to turn up in their - or their voters' - backyard. Out of sight, 600 miles south of the mainland, Okinawa was the perfect dumping ground. Recently, after decades of procrastination, the two governments finally agreed to remove a military port - only to rebuild it nine miles up the coast.

This perhaps has been the most crucial change of the last six weeks. Slowly but steadily, the outrage at the rape has spread throughout Japan. Dozens of other prefectures and local assemblies have passed motions condemning the incident, and the Status of Forces Agreement (SOFA), under which the suspects enjoyed the privilege of military custody until they were charged.

Governor Ota has another powerful card up his sleeve. The land occupied by the bases is leased to the Japanese government by thousands of small landowners. Many of them are glad of the guaranteed rent, but 3,000 'anti- war landlords' refuse to sign the necessary documents as a matter of principle. In the past, the land has been appropriated by the order of the governor but three weeks after the rape, Ota announced that he would not sign the requisition order.

The announcement caused consternation in the Japanese government. A high- ranking Defence Ministry envoy was dispatched to Okinawa to talk Ota round, only to be left kicking his heels as the Governor, in defiance of all the rules of Japanese diplomacy, refused to see him. Ultimately, the government can force the issue, but only through lengthy and embarrassing public hearings. For Tokyo, the prospect of forcing the land requisitions on Okinawans, 80 per cent of whom support their governor, is almost unthinkable. But the alternative is equally disastrous: if nothing is done, the American military will be in illegal occupation of key portions of its own bases.

The stakes get higher as time goes on. If proceedings do not begin soon, it will be too late to renew the leases before their expiry next spring. Governor Ota shows no sign of yielding. Given real and concrete concessions from Tokyo, however, he may have little choice. Whatever happens, though, the rape of the nameless 12-year-old will never be forgotten. "You might call it a coincidence," says Shoichi Chibana, one of the anti-war landlords, "but I'd say there's something essential and historical about the timing of this rape. Her happiness has been sacrificed, but every time 4 September comes around, we will remember."