Yes, Putin is a monster. No question about it. Most leaders in the world are monsters of one sort or another. All of the deposed or endangered secular leaders of the mideast are or were monsters. But most of them kept the radical islamists in line, were no threat to the United States and promoted some semblance of stability in an unstable region.
When dealing with international relations, if you want to shun dealing with monsters you are going to be quite isolated.
Russia eventually re-taking Eastern Europe and grabbing control of the oil/gas-rich Middle East is not a threat to the US and its allies??