...I make the following comments:
* we all know he's an empty shell with no consistent principles, able to be influenced by the last thing he heard, and his fragile buffoon ego always wants to claim he's a "winner". It's not surprising that one minute he'll decide to sound tough on Russia/Putin, and the next he'll try to walk it back a bit;
* that's pretty much what we are seeing now. Look at these tweets and their tone of "Jeez, don't blame me for things being bad with Russia. If it weren't for those damn Democrats persecuting me I'd have it all back on track and things would be great with Russia":
* there is also the possibility that his peanut brain is just smart enough to think "I'd better sound tough on Putin so that people don't think I'm under the Russian thumb."
* tax returns? A very plausible theory is that Trump is scared of the investigation not because he was closely involved in collusion re Russian interference in the election (although his having some knowledge of seedy contacts by his staff is quite likely), but that the investigation will turn up financial ties to Russians that he does not want to see disclosed. Again, this would justify a "better sound tough, but still want to be friends with Russia" back and forth in his rhetoric.