All that happened how many years ago? The last war in Vietnam was more than 45 years ago and it lasted a month only.

North Korea war - Sino went in because MacArthur was threatening to enter China even though Truman was against it. The was getting way too near China's borders and if North Korea fell, it would threatened Mao's position as KMT would attack from the South and US can attack from the North

India Sino conflict - The whole thing was caused by British imperialism who simply draw up borders without consent. This border dispute is still on-going today as even KMT time, they already disputed the borders drawn by the Brits when Qing Dynasty was at its weakest

Sino-Vietnam war - The short war was caused by Vietnam's invasion of Cambodia and China wanted to punish Vietnam for choosing Soviet Union instead of China. US actually opened their embassy in China during this period as US still viewed Vietnam as the enemy during this time. US actually did not object to China's invasion of Vietnam

USSR Sino conflict - This is a conflict due to Cold War and the breakup of communist bloc. It did not went into full scale war but just skirmishes. The war actually benefited China in the long run as US started diplomatic relationship with Mao and Taiwan lost its status as representing China forever

Invasion of Tibet - Tibet was already part of Qing Dynasty and considered part of China for more than 400+ years. Mao invaded Tibet to take back China's traditional borders and if anyone look at the official maps of China in early 20th century before WW2, it has always included Tibet as part of China

Russia Ukraine is not totally unjustified especially the area where it has huge population of Russians

As for Israel Palestine, Israel actually won the war fair and square against the Arabs. So, can you really say they don't have any rights over the lands at all?

As for Tibet, it was part of China for more than 400 years before the 20th century. All the maps of the world in early 20th century also show Tibet as part of China. Even KMT also consider Tibet as part of China when they were ruling China. So, who are you to say Tibet is not a part of China.

If that is the case, India was never a unified country and consists of small kingdoms. It was the Brits who created the borders of modern India, So, India is not justified too?

Does every country in the world today are formed with self-determination?

If you want to question this, then most countries in the world today won't have the same borders as today

Fact is no matter how people like you want to deny, Tibet today is undeniably a part of China. Similarly, Israel as a country is also an undeniable fact too