text: I've heard of fake news but now you are supplying fake history!
  
  China 1900 - Boxer Rebellion
  For two months the Boxers occupied the capital and besieged the foreign legation district, where the foreign community and a large group of Chinese Christians barricaded themselves within the legations. The foreigners managed to resist repeated Boxer attacks until a multinational force finally fought its way in from the coast and reached Beijing, lifting the siege. U.S. marines played a key role in defending the legations during the siege and also joined the multinational force that crushed the Boxers.
  That's your "invasion"???
  
   Korean War
  US and/or the UN force fighting the N. Koreans and the Chinese, who "attacked them" to back the N. Koreans, but 'never' crossed into China.
  (Maybe your "epic bloody battle along the border" was a video game you once played.)
  
  Vietnam.
  US was invited into Vietnam.