The papers Rostow wrote urged a policy of "graduated" pressure as the United States would steadily increase the level of bombing to such a point that it would ultimately lead to the destruction of North Vietnam's nascent industry. Unlike most American decision-makers, who knew nothing of Vietnam's history, Rostow had done much reading on the subject, and had learned that over the centuries that Chinese elites considered Vietnam a lost province which they would one day reclaim (Vietnam had been a Chinese province from 111 BC to 938 AD), leading to a long series of Vietnamese-Chinese wars as successive Vietnamese emperors fought off attempts by the emperors of China to incorporate Vietnam into the middle kingdom. Knowing of the full depth of the Sino-Vietnamese enmity, Rostow reached the conclusion that Ho Chi Minh would not want his nation to draw too close to China, and as such, could not risk the destruction of North Vietnam's industry, which would leave North Vietnam entirely dependent upon China. One of Rostow's opponents, George Ball, argued that Ho's Vietnamese nationalism would make him an Asian version of Josip Broz Tito of Yugoslavia, a communist leader who wanted his nation to be independent of both Moscow and Beijing. Ball argued that South Vietnam was a poor and politically unstable ally that contributed little to American national security, and allowing Ho to reunify Vietnam would pose no danger to the United States. Rostow, by contrast, argued that South Vietnam was the crucial to American national security and to allow the first "domino" to fall would cause the other "dominoes" in Southeast Asia; in his mind, losing any nation to communism, even it was of the Titoist type was unacceptable.