Just some quick examples:
* Recommending American de-nuclearization while stating that Russia is no longer a threat to America.
* Dismantling cybersecurity programs that are intended to identify and counter Russian hacking efforts.
* Peace negotiations with Ukraine and Russia that require no concessions made by Russia.
All of these actions are being taken despite polling poorly with Americans. You could say that none of these definitively proves that there is Russian leverage over Trump and you would be technically correct. The flip side of that coin is that you also can't explain why these actions are in America's best interest.