BEIJING â€” Bitter maritime disputes between China and its neighbors have recently sent fighter jets scrambling, ignited violent protests, and seen angry fishermen thrown in jail. But beneath all the bellicose rhetoric and threatening posture, China also has been waging a quiet campaign, using ancient documents, academic research, maps and technical data to bolster its territorial claims. The frenetic pace of such research â€” and the official appetite for it â€” comes after decades of relative quiet in the field and has focused heavily on the two hottest debates: Chinaâ€™s quarrel with six other nations over a potentially oil-rich patch of the South China Sea and its tense feud with Japan over a small sprinkling of land called the Diaoyu Islands by the Chinese and the Senkaku Islands by the Japanese. For some Chinese academics, the now-heavy demand for such work marks a near reversal of what they experienced early in their careers. In past decades, some say, territorial disputes were often considered too sensitive a topic because China was leery of disrupting its relations with its neighbors. â€œThe government always emphasized the stability of bilateral relationships in the past, so doing public research on the Diaoyu Islands, for example, was not practical,â€ said one Chinese professor. â€œYou couldnâ€™t write a thesis on it .â€‰.â€‰. there would be nowhere to publish such articles publicly.â€ Even now, the topic remains sensitive. The professor spoke on the condition of anonymity because, he said, others have been punished in the past for speaking too openly on such matters. But after an especially bitter dust-up in 2010 between China and Japan, some Chinese scholars say, officials worried that the limited research had hurt Chinaâ€™s ability to make strong territorial claims, leaving it at a disadvantage with others, such as Japan, whose research community faced fewer constraints. Chinaâ€™s attention to maps and other documents has intensified since â€” bringing with it spats of a new kind. The most recent began shortly after Christmas when a Japanese publication posted what it claimed was a 1950 Chinese government document unearthed in Chinaâ€™s own archives calling the disputed islands by their Japanese name, implying that Beijing then regarded the islands as Japanese. Chinaâ€™s embassy in Japan sidestepped the question of the documentâ€™s authenticity, saying that â€œeven if the document exists, it wonâ€™t change the consistent position of the Chinese government.â€ The embassy later dismissed the whole thing as a â€œJapanese attempt to support their wrong stance with an anonymous reference document.â€ But just weeks afterward, with little explanation, Chinaâ€™s Ministry of Foreign Affairs shut down access to a large portion of its archival documents. A staffer at the archive said last week that the closure was â€œdue to an upgrading of the systemâ€ but was unable to say when the work would be complete. Bitter wrangling over small islands The bitter feud between China and Japan over a handful of rocky outcroppings may seem frivolous. But the fight carries great weight domestically for both countries â€” and huge implications for the United States. If the military bluster and threats continue, U.S. diplomats and experts fear, it could lead to a military miscalculation and, in the worst case, an actual war that could draw in the United States, as an treaty-bound ally of Japan. Chinaâ€™s increasingly aggressive posture on such claims is driven by a heady mixture of nationalism and strategic and economic interests. In a sign of just how important such claims have become, it has been widely reported in foreign media â€” though not confirmed by the government â€” that Chinaâ€™s new top leader, Xi Jinping, was personally put in charge of a task force responsible for the Diaoyu Islands claim in September, shortly before he was formally named to lead the ruling Communist Party. That same month, tensions shot up after Japan announced it was buying the disputed islands from private Japanese owners for nearly $30 million. The move prompted riots in China, and trade between the two Asian powers suffered. Diplomatic relations sputtered. And Chinese and Japanese ships clashed on the seas, ramming and spraying each other with water cannons. In the five months since, there has been a flurry of official interest in Chinaâ€™s documentary backing for its territorial claims. Several seminars and conferences were convened by government-affiliated think tanks. At one high-profile gathering in Shanghai, scholars concluded with a five-point consensus â€œto pool together our wisdomâ€ and â€œto safeguard the sovereignty of the Diaoyu Islands and to oppose Japanâ€™s violation.â€ Chinaâ€™s State Council issued a 5,200-word white paper that laid out, point by exhaustive point, Chinaâ€™s case. This fall, key historical documents, atlases and journals were assembled into an exhibit at Chinaâ€™s National Library. The libraryâ€™s official statement included a sneering reference to the â€œsheer historical lieâ€ of Japanâ€™s claims, and the displays included records from imperial envoys stretching back to the Ming dynasty in the 1300s. Academic credibility Maps â€” ancient and modern â€” have been a particular area of focus, with the governmentâ€™s scientific and academic subsidiaries pumping out atlases, three-dimensional graphs and sketches of both disputed areas. New passports were outfitted with maps that include a dotted area that pointedly marks Chinaâ€™s claimed portions of the South China Sea. Even weather reports on state-run television have been amended to add forecasts for disputed areas. Some international scholars, however, question how much credibility the recent burst of historical studies and technical data adds to Chinaâ€™s claims â€” especially given the fact that most think tanks and universities in China remain firmly in the grip of the Communist Party and its government. â€œIf you look at the academic documents and arguments, especially on the Chinese side, the conclusions across the board look like one unified piece of concrete,â€ said Jean-Pierre Cabestan, head of government and international studies at Hong Kong Baptist University. â€œItâ€™s concerning on an academic level to talk to people without a shred of doubt affecting their mind. It suggests a lack of ability to seriously evaluate the other sideâ€™s arguments. The whole truth is often more complicated.â€ Chinese scholars defend their work as sound, even as some are trying to build credibility by relying less on Chinese documents and instead finding foreign materials to support Chinaâ€™s claims. â€œWe are not lacking in domestic evidence,â€ said Li Guoqiang, an expert on disputed territories at the Chinese Academy of Social Sciences. â€œBut it would be even more convincing to the international community if we can use the evidence of our opponents.â€ Most acknowledge that their research alone isnâ€™t likely to solve such intractable territorial disputes. But they argue that it does provide a safe arena for conflict in an era of mounting tensions. In this monthâ€™s latest, Japanese officials said a Chinese naval vessel had threatened a Japanese warship by locking a weapons-guiding radar on it. With the way the region is heating up, even academics working to support Chinaâ€™s claims wonder where the conflict might ultimately lead. â€œI worry about the Sino-Japanese relationship, especially this year,â€ said Zhou Yongsheng, an expert at China Foreign Affairs University in Beijing. â€œIf [Japan] keeps following their current policies, the situation will deteriorate even worse. And China is very assertive to take countermeasures if necessary. It could get unpredictable and out of control.â€ Zhang Jie contributed to this report.