Lao didn't involve in the war but Vietnam attack Lao by direct order from Kremlin, China attack Vietnam in 1979 because Vietnam started a war in IndoChina, China fought the 1979 border war with Vietnam force Vietnam to reserve your arm troop in case China want to start another war with Vietnam, Vietnam couldn't control of IndoChina partly deal to the fall of Soviet Union.
you lie.
China backed Khmer Rouge to attack Vietnam first.
we don't let in the same time both Khmer Rouge and China attack us.