Months after the Simla agreement, which China considered illegal, China set up boundary markers south of the McMahon Line. T O\'Callaghan, an official in the Eastern Sector of the North East Frontier, controversially relocated all these markers to a location slightly south of the McMahon Line, and then visited Rima to confirm with Tibetan officials that there was no Chinese influence in the area. The Simla Agreement violated the Anglo-Russian Convention of 1907, which (although mostly unrelated to the Himalayan region) stipulated that neither party was to negotiate with Tibet \"except through the intermediary of the Chinese government\". Because of these treaty constraints it was not until the 1930s that the British started to officially use the McMahon Line on maps of the region. China took the position that the Tibetan government should not have been allowed to make a such a treaty, rejecting Tibet\'s claims of independent rule. For its part, Tibet did not object to any section of the McMahon Line excepting the demarcation of the trading town of Tawang, which the Line placed under British-Indian jurisdiction. However, up until World War II, Tibetan officials were allowed to administer Tawang with complete authority. Due to the increased threat of Japanese and Chinese expansion during this period, British Indian troops secured the town as part of the defense of India\'s eastern border.
