China invaded, conquered and occupied Vietnam in 221BC, 111BC, AD43, the 13th Century and in 1407. The Chinese did not leave voluntarily. In 1979 China attacked Vietnam in an unsuccessful attempt to expand their border to the South. Armed Chinese attempts to occupy the Spratley Islands (Vietnamese territory) are ongoing.
Tibet was a fully independent country from 1911 (when the Chinese left) until Communist China invaded in 1950, not long before they attacked into North Korea. A Tibetan uprising in 1959 was crushed and extremely repressive measures were instituted against the populace. Anti-Chinese demonstrations resumed in the 1980's and were violently put down. Chinese martial law was imposed in 1989.
Wonder which "legitimate part of China" is next to be reclaimed.
Given motive, opportunity and means all countries have expansionist tendencies. That's how countries evolved from tribal enclaves. Nations that were once Empires know that best of all. The trick is for countries to act like grown-up members of the world community and act in accordance with recognized International Law.
[This message has been edited by StbdD (edited 26 April 2001).]