And if they did how many times did it happen?
I mean direct conflict ie Russian's firing on Americans, not proxies fighting each other.
The only time I am aware of is during the Russian Civil War in August 1918. The US and other Allied countries sent troops to intervene to prevent German capture of supplies (WW1 was still going on), try to get Imperial Russia fighting the Germans again, and defeat Bolshevism.
13,000 American troops landed:
When WW1 ended, the Allies stayed to fight against the Soviet revolutionaries until 1920.
Source:
The History of the American Expedition Fighting the Bolsheveki, by Moore and Mead