India has formally protested to China following the alleged arbitrary detention of an Indian citizen at Shanghai airport, escalating tensions between the two nations. The incident occurred on November 21 when Pem Wang Thongdok, a traveler from India’s northeastern state of Arunachal Pradesh, was held for 18 hours during a layover en route to Japan. Chinese authorities reportedly deemed her passport invalid, citing Arunachal Pradesh as Chinese territory, which Beijing refers to as Zangnan or Southern Tibet. India firmly maintains that Arunachal Pradesh is an integral part of its territory. This episode adds to the existing strain in bilateral relations, already marred by a military standoff along the Himalayan border, trade restrictions, and competing regional interests. The dispute over Arunachal Pradesh remains a significant obstacle to improving ties between the two nuclear-armed neighbors. China’s Foreign Ministry spokesperson Mao Ning defended the border inspection authorities, stating the case was handled lawfully and denied any detention or harassment. India’s Foreign Ministry countered, asserting that Arunachal Pradesh is an inalienable part of India and criticized China’s actions as violations of international air travel conventions and its own transit regulations.