A useful idiot, in Lenin's terms, but too much of an idiot to realize it. That is the only innocent explanation. And it is a distinct possibility - he has spent 70+ years amassing evidence to support the assertion that he is an idiot.
But we live in amazing times if the best-case scenario is that the president is too stupid to realize he is being manipulated by Putin. Jesus. Just look at this new report below.
Link: https://www.cnn.com/2019/01/17/politics/nyt-reporter-trump-putin/index.html