Tensions between India and China have been growing over the last decade, and now India is paying more attention to Chinese espionage inside India. There has already been a lot of Chinese spying on India via the Internet but now India is taking a closer look at Tibetan exiles. Most (about 70 percent) of the 150,000 Tibetan exiles are in India, which provides economic assistance and diplomatic protection. The exiles have been coming since the 1950s (when China invaded Tibet) and especially after China crushed the 1959 Tibetan rebellion. The exiles have long complained about Chinese agents among the new refugees and India has tried to be helpful. But those accused were often simply reporting back to their Chinese paymasters what was going on in the refugee community. That could sometimes have disastrous consequence for Tibetan rebels back in Tibet but it did not violate Indian laws. Now that attitude has changed because some of these spies are believed to be reporting mainly information about the Indian military. This is a different matter entirely and the Indians are cracking down, although first they have to find actual Chinese spies who are breaking Indian law.
China has been recruiting Tibetans for its military and espionage services and training some of them to fake being anti-Chinese Tibetans fleeing oppression and seeking sanctuary in India. These agents are trained in the use of modern espionage techniques, and once they establish themselves in India they are supposed to organize and run networks of spies (with cash and technical assistance from China). All this is part of the growing tensions between the two countries over Chinese claims on Indian territory. The problem here is that China is claiming a lot of Indian territory in addition to the 38,000 square kilometer chunk of land in Kashmir that China seized after a brief war with India in 1962. Now India is alarmed at increasing strident Chinese insistence that it owns the northeastern Indian state of Arunachal Pradesh, as well as more of Kashmir.
All these border disputes have been around for centuries but became more immediate when India and China fought a short war, up in these mountains, in 1962. The Indians lost and are determined not to lose a rematch. But so far, the Indians have been falling farther behind China. This situation developed because India, decades ago, decided that one way to deal with a Chinese invasion was to make it difficult for them to move forward. Thus, for decades, the Indians built few roads on their side of the border. But that also made it more difficult for Indian forces to get into the disputed areas. Now that is recognized as a mistake, but fixing it is not easy and will take years.
The source of the current border tension goes back a century and heated up when China resumed its control over Tibet in the 1950s. From the end of the Chinese empire in 1912 up until 1949 Tibet had been independent. But when the communists took over China in 1949, they sought to reassert control over their "lost province" of Tibet. This began slowly, but once all of Tibet was under Chinese control in 1959, China once again had a border with India and there was immediately a disagreement about exactly where the border should be. That’s because, in 1914, the government of newly independent Tibet worked out a border (the McMahon line) with the British (who controlled India then). China considers this border agreement illegal and wants 90,000 square kilometers back. India refused, especially since this would mean losing much of the state of Arunachal Pradesh in northeastern India and some bits elsewhere in the area.
In addition to Arunachal Pradesh (83,000 square kilometers and only a million people) China also claims part of Kashmir (Uttarakhand, with 53,566 square kilometers and ten million people). The 4,000 kilometer border with China is actually with Tibet and China has been building a lot of roads, railroads, and military facilities near the Indian border. Now China is sending more spies, in the form of Tibetan refugees, into India to get a close look at whatever defenses the Indians might have. More of these agents are being found and the Indians believe that there are many more (possibly dozens) that have not been detected.