WITH the Cold War all but over, it is sometimes hard to believe a country such as the United States is still crawling with foreign agents out to steal its secrets. Even harder to imagine is the relatively quiet city of Charlotte, North Carolina, as the backdrop to a classic drama of espionage and intrigue. But if the days of Eastern bloc spies loitering on street corners have all but faded, there appears to be another communist force willing to keep the cloak and dagger in working order. If Federal Bureau of Investigation (FBI) agents are to be believed, a Charlotte restaurateur has been spending the past six years on a prospective shopping expedition for some of the most sensitive military technology in the US arsenal. And the nation that wants it is China. The news that Kao Yenmen, a Chinese national, had been arrested on December 3 and implicated in trying to buy military equipment for export was enough to whet the appetite of any followers of international intrigue. But what followed was a virtual news blackout, raising more questions than it answered. And now, with Mr Kao voluntarily opting for deportation to Hong Kong this weekend, the immigration hearing that promised to provide a full public airing of the facts will not take place. But enough is known to piece together a spy tale that seems all too plausible. An FBI official told the Sunday Morning Post the case had gone all the way to the higher echelons of the State Department. It is not difficult to see why. First, the hardware. Top of the list was a state-of-the-art Navy Mark 48 Advanced Capability torpedo, which Mr Kao was allegedly offering US$2 million (HK$15.5 million) to buy. The torpedo, the most advanced water-launched missile in the US arsenal, has a greater range (37 kilometres) and speed (55 knots) than anything produced so far, and is a highly classified piece of technology. According to the FBI, China also enlisted Mr Kao to spend US$4 million on two F404-400 engines, made for the FA-18 Hornet jet fighter, and an AN-APG-68 radar system used in F-16 fighter jets. ''These items would have been extremely detrimental to the US should they have fallen into hostile hands,'' FBI special agent Charles Richards said. Dr George Carver, national security expert with the Centre for Strategic and International Studies, said he was not surprised at the idea of China trying to secure such items. ''This would not be the first time China, or any number of other nations, has tried to get its hands on technology we don't want it to. ''With things such as torpedoes, the idea is to make sure your state-of-the-art is at least two generations ahead of the others' state-of-the-art.'' Mr Kao, with a Chinese wife, Kathy Kao Ying Mui-chen, and two US-born children, had been tracked by agents for six year. What brought him to the attention of the authorities is as unclear as much of his earlier history. Born in China in 1939, reportedly in Fujian province, he told his neighbours in Charlotte that he went to the Soviet Union to train as a surgeon. He said he was imprisoned during the early 1960s, and later went to live in Hong Kong. When he arrived in the US in 1971, he found he could not practise medicine, and after meeting his wife, started up a fast-food business in Charlotte. He is also said to run a trading company. Vehemently denying the allegations, Mr Kao is vague about how he ended up in the FBI's sights. He claimed he was framed by an unnamed American with ties to China, but refused to elaborate. One of the keys to the puzzle is Ron Blais, an army veteran turned private investigator. He said he was approached by a mystery Charlotte businessman in 1987 to enlist his help in stealing the Mark 48 torpedo. Again, the man is not named, but is presumably the same person Mr Kao said framed him. Mr Blais informed the FBI, which promptly enlisted his help as an undercover agent to find out who was involved. Questions have been asked as to why the probe lasted six years, culminating in just one arrest - that of Mr Kao, who has not been criminally charged. But it can be assumed that with Mr Blais' help, the US Government took advantage of the time to find out more about China's spying activities than the mainland ever discovered about US military hardware. Mr Blais told an immigration hearing that he travelled to China three times with Mr Kao, meeting officials in the country to discuss the purchases. This was in addition to about 300 meetings with Mr Kao in Charlotte, many with the knowledge of Mr Kao's wife, who acted as his assistant when he was away, Mr Blais alleged. Mr Blais is in no doubt the FBI got the right man, claiming to have him on video and audio tape, and in writing, discussing the deals. Other alleged spies, who met with the agent during the period of the investigation, have recently gone back to China - possibly assuming their cover had been blown. Claiming last week he was only held because he was Chinese, Mr Kao said: ''If I did it, why not charge me as a criminal?'' It is a valid question, but not hard to answer. The FBI is thought to be unenthusiastic about the prospect of a long criminal trial, where its agents would have to provide detailed evidence on their activities. The solution was to find an excuse to deport Mr Kao without a trial. And he had conveniently overstayed his business visa. Even so, there was the prospect of a bitterly contested deportation hearing next month, when the judge would certainly have demanded a full explanation of the government's case. But in a bizarre twist, Mr Kao saved the FBI from that fate. Claiming he had been denied proper medical treatment in his Atlanta jail cell, and was losing weight from lack of food, Mr Kao's family called for an urgent hearing, where he admitted the visa violation and agreed to be sent to Hong Kong. It was better to live abroad, he said, than die in a US jail. If the suspect is innocent - or even if he is not - his family's future does not appear to be a happy one. Mrs Kao will stay behind with their 18-year-old son and 20-year-old daughter to run the restaurant, separated from her husband, who says he has no home or work in Hong Kong. ''The future is a long story,'' Mrs Kao said. ''I'll just go to work and raise my two children.'' Meanwhile, as he prepares to land in his new home, Mr Kao still claims to be as mystified as many observers. ''Why would I have to spy for China? Both my children are American. Why would I steal American technology?'' While one struggles to answer Mr Kao's questions, others must be raised on how the incident will affect US-China relations, already strained on the issue of military arms proliferation. And while refusing to explain what they have in mind, FBI agents continue to stress the operation will not end when Mr Kao leaves the US. One would not be at all surprised to discover China thinks the same way.