As The Republic of Vietnam and the United States performed most of the defense of Southeast Asia against Communist Aggression many other nations sent men, material and support in various means during the conflict.

Here is article by Jesse Greenspan posted on https://www.history.com/news/vietnam-war-combatants#section_7 about other  countries who were also involved in the conflict.

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Republic of Germany
During the thirteen years of the conflict 

Italy
​During the thirteen years of the conflict 

Malaysia
​During the thirteen years of the conflict 

Singapore
​During the thirteen years of the conflict 

Republic of China (Taiwan)
​During the thirteen years of the conflict 

Great Britain
​During the thirteen years of the conflict 

Spain
​The Secret support of the United States in Vietnam.  https://english.elpais.com/elpais/2012/04/09/inenglish/1333979983_253264.html

Morocco 
​During the thirteen years of the conflict 

Phillipines
​During the thirteen years of the conflict 

India
​During the thirteen years of the conflict 

Japan
​During the thirteen years of the conflict 

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