Actually the HUAC (house unamerican activities committee) was established by a democrat majority in congress. It was a pretty good idea to expose the communist influence in society but when attitudes changed the liberal media managed to blame the whole thing on a republican senator. Little ignorant bean counter Harry Truman signed an order to dismantle the OSS after WW2 and scatter the responsibilities among the State Dept and the Army. It was a bad idea. Truman also dismantled the greatest Fighting Force in the world and we weren't ready for Korea either from a military or an intelligence standpoint. The Cold War and the communist revolution seemed to come as a surprise to the government.
Most of us could go through WWII and find thousands of errors, thousands of bad decisions from platoon commanders up to the president. If America were a dictatorship certainly some of the political decisions made during the war and after would have been made differently. But it's not a dictatorship and with the war ended, the American people may have wanted to get back to a normal life; they had gone through the Great Depression, and then WWII and now they wanted to resume a life. The GI's also figured they had done their job and wanted to come home and politicians responded.
It takes no genius today to go back and see errors and miscalculations, and there are some biggies involving thousands of lives, but that's the nature of wars. And I guess it is the nature of post-war generals to point out the errors that were made.
As one general stated, in battle nothing goes as planned.