The Second Chechen War veteran attacked the men in the city of St Petersburg in the north-western Russian region of Leningrad Oblast.
The incident was filmed by a CCTV camera and later posted online.
According to reports, the veteran was about to order some food in a local fast-food restaurant when he heard male voices talking about his bag.
After one of the men reportedly said that the bag was “feminine looking” and its owner might be “gay”, the former soldier lashed out.
The clip shows the unnamed veteran, dressed in a black cap, taking the bag off his shoulder before punching one of the men hard in the face – knocking him to the ground.
Another yob approaches him before the soldier clobbers, sending him to the floor.
A third man, who appears to be trying to calm the situation, is also decked by the no-nonsense veteran.
He then starts pummelling the first yob before grabbing a chair and using it to beat at least two men.
The third group member explains his case to the veteran and he goes over to apologise to the restaurant staff before shaking hands with the peacemaker.
Local media said that the ex-soldier fought in the Second Chechen War, which ran from 1999 to 2009.
It was fought between the Russian Federation, the eventual victors, and the unrecognised Chechen Republic of Ichkeria in the territory of Chechnya and the border regions of North Caucasus.
Social media users have come out in support of the veteran.
Lena Semechkova said: “Those bullies got what they deserved! Love it!”
And Andrey Laptev commented: “The veteran is awesome. Respect!”
According to reports, the police are not investigating as the bullies did not report the veteran.