The Korean War 1950-1953, against Red China. Nationalist China (Taiwan) was an ally with the US.
Taiwan is the full name of the island. The Republic of China is the nation that occupies the island.
china and japan fought against each other for control of Korea
US & UN (and South Korea, if they weren't part of the UN) against Red China & North Korea.
Japan fought Russia to try and obtain more power in China.
That would be Japan. Though it isn't necessarily an Island, much less a country.
Japan
The country was Japan, which is actually several islands.
China
they fought against the axis powers in WWII and they fought against America in the Vietnam War
Japan
China
they fought against Germany
Japan
There is Taiwan island, a bit higher than 23N latitude, but now it is not a nation. Taiwan is territory of China.
The Korean War 1950-1953, against Red China. Nationalist China (Taiwan) was an ally with the US.
JAPAN