AMID THE FLAG waving, apple-pie feasts and endless strains of God Bless America surrounding the return of the freed spy-plane crew to United States soil, it is easy to forget that a little piece of America remains on Hainan Island. With nose cone destroyed and propellers damaged, the EP-3E Aries II electronic-surveillance plane remains on the runway of Hainan's Lingshui air base, after crash-landing on April 1. It is now clear the crew's return - after Washington's claim to being 'very sorry' following the collision with a Chinese jet fighter, which appears to have killed pilot Wang Wei - is by no means the end of the affair. Not surprisingly, then, the plane itself is swinging into focus. Washington wants it back, swiftly and unmolested. But Beijing is reserving its right to hold on to it for the time being for 'investigations'. Yesterday, the war of words started again as both sides positioned themselves ahead of a joint meeting in Beijing on Wednesday. 'This incident is not over yet,' warned President Jiang Zemin's spokesman Zhu Bangzao, during a mission to Havana, Cuba. 'The US side has to assume all responsibilities in this matter and give an answer to the Chinese people,' Mr Zhu said, adding that the Chinese had every right to hold on to the plane. US Secretary of State Colin Powell was not amused. 'I have to assume they've been all over it . . . But it is our plane, and we expect it back,' he said. Defence Secretary Donald Rumsfeld, who had been muzzled during the State Department's delicate talks, was off the leash in his first major briefing on the saga at the Pentagon. 'We have every right to fly where we were flying,' he said, referring to the plane's location 58-nautical miles southeast of Hainan at the time of the mid-air prang. 'They have every right to come and observe our flight. What one does not have the right to do is to fly into another aircraft . . . the [Chinese] F-8 pilot clearly put at risk the lives of 24 Americans. 'When they landed, they were greeted with armed crew, so I suspect the people at the airfield knew they were coming,' Mr Rumsfeld added. The comment appeared geared towards an intense debate. Leading international lawyers warned of many shades of grey relating to the rights and responsibilities of states receiving planes in distress. In theory, the plane is American territory. Like ships, military planes and commercial airliners are registered and 'flagged' to a particular nation. The crew of the American plane now insists that shortly after the collision, it made about 25 to 30 mayday calls. No response from the Chinese side was detected, despite the presence of a second Chinese fighter that mainland military sources have suggested was prepared to shoot the American plane from the sky. The American plane crash-landed at Lingshui and was quickly surrounded by armed Chinese guards. The 24 crew held them off while systematically destroying computers and intelligence documents in accordance with a checklist. As Washington demanded the immediate return of the crew, it also stressed China must keep out of the plane, warning it is American sovereign territory, and to allow for the plane to leave as soon as possible. If the plane had been a commercial aircraft, China's obligations would be more cut and dried, legal experts said. The internationally accepted Chicago Convention for Civil Aircraft ensures sweeping obligations for nations receiving planes in distress. But the convention does not apply to military aircraft, a fact noted by US military documents. The Commander's Handbook on the Law of Naval Operations produced by the US Naval War College makes this clear, yet implies sweeping obligations on a host nation under long-accepted international practices. It states: 'The convention, by its terms, does not apply to intruding military aircraft.' And continues: 'The US takes the position that customary international law establishes similar standards of reasonableness . . . with respect to a nation's response to military aircraft that stray into airspace through navigational error or distress.' US intelligence sources said they were aware their Chinese counterparts, like many countries, had copies of the handbook. Ruth Wedgwood, an expert on international law at Yale, said she believed Washington was on strong ground with its demands but China might see room for manoeuvre, given the lack of a formal convention and the fact it claims not to have heard the mayday call. 'The bottom line here is that what we call customary law - that is, feasible obligations built up over many, many years - is very strong here, and China might well be on shaky ground,' Ms Wedgwood said. Such law is wrapped up in the concept of 'safe harbour' for foreign ships in distress across the world's oceans, which dates back hundreds of years. Military ships have always had powerful protection under such concepts and were considered 'deeply sovereign' by lawyers. Noting the plane was allowed to land without military intervention - such as being shot at - she said there could be 'no question' China was aware of the identity of the plane. 'It does appear they knew it posed no military threat,' Ms Wedgwood added. Given the sensitivities surrounding the case on both sides - the US has still not formally explained what its plane was looking for - it is likely they will try to solve the matter internally, with Wednesday's meeting in Beijing being the start. If the plane issue remains unresolved, either side could mount legal action through the International Court of Justice at The Hague. Such a case would prove a fascinating test of the grey areas, legal experts said. It would also confirm that every such incident is different, with this case already throwing up many unique aspects. This would make a court case a time-consuming, complex and difficult course for either nation. The official Washington position has sought to skate over the murkiest areas of the law with firm statements - repeated by President George W. Bush himself - that China's obligations are clear under 'international law and practice'. Such statements also skirt the fact that the US has, on occasion, dodged similar appeals from foreign states, most notably during the Cold War. And Pentagon officials have privately admitted that intelligence services still run operations to obtain military technology and equipment from a range of potentially hostile nations - including China - by exploiting any means possible. 'When it comes to hard-boiled military intelligence, you might say it is a case of all being fair in love and war,' one intelligence source said. 'This is not a Sunday picnic.' Perhaps the most glaring example occurred in 1976 in Tokyo. A Soviet pilot wanted to defect and flew his MiG-25 fighter - then a state-of-the-art plane - to Japan, presenting a glittering intelligence prize to Western agencies. Moscow launched formal diplomatic protests and demanded its return - much as Washington is doing now. The Russians eventually got the plane back, in pieces and boxed in packing crates. American experts had spent nine weeks stripping it and examining the parts. But Ms Wedgwood cautioned against swift judgments. Warning that no incident was ever like the next, she said a defence could be mounted for such action. The defector essentially handed his plane over as a gift - it was not in distress - so receiving nations might not have faced the usual international obligations. 'That case seems very different from this one . . . and quite possibly defensible,' she said. One remaining unknown is exactly what is left for the Chinese to glean from the damaged EP-3. The plane itself - a lumbering Cold War relic that has been in service for more than three decades - is no hi-tech prize. On board, however, is some of America's most advanced and compact eavesdropping technology. The crew possessed the ability to tap and decode all manner of Chinese military communications, from inland radar and missile sites to fax machines and mobile phones. Some intelligence analysts have described the plane's kit as the 'crown jewels' of electronic surveillance, far more advanced than anything China could otherwise get its hands on. However, some equipment was dumped over the South China Sea as the plane struggled to Hainan. Then there was the 15 minutes the crew spent systematically destroying the rest of it on the ground in Hainan. 'I am confident they completed the major portion of their checklist,' Mr Rumsfeld said. He declined to elaborate on what technology or intelligence equipment might still be left on board. At the Pentagon, officials claimed there was not much technology left worth China's effort. 'We are confident the main value left in the plane is its symbolic worth,' one senior official said. 'That is not to be dismissed easily. That is why we want it back.' Greg Torode ( torode@scmp.com ) is the Post's Washington correspondent