A police chief in Ohio is GOING OFF on Kanye West -- tearing the guy apart for comparing himself to cops and soldiers ... saying Kanye has NO CLUE about the real dangers they face. The cop with the beef is Brimfield Police Chief David Oliver ... who says he was listening when Kanye told a media outlet that he puts his life on the line at his rap concerts ... just like cops and soldiers. Chief Oliver was so angry, he posted an open letter to West on the department's Facebook page ... saying, "You sir, are as misguided as they come." The majority of the letter is dripping in sarcasm, mocking Kanye for the ridiculous comparison: "Since you are accustomed to danger, from your life as an international rapper, I am strongly encouraging you immediately abandon you career as a super star and join the military." "After joining, I would like you to volunteer to be deployed in Afghanistan or one of the numerous other forward locations where our men an women are currently serving. When the Taliban starts shooting at you, perhaps you could stand up and let the words flow." "I’m sure they would just drop weapons and surrender. You could quite possibly end all wars, just from the enemy being star-struck." The letter ends, "What I do not get is you EVER comparing what you do for a living to our heroic military members, who are always in harm’s way… and my brother and sister police officers who have to go to work carrying weapons and wearing a bullet-proof vest to protect themselves." "Check yourself, before you wreck yourself….Chief Oliver."