One of those Presidents was different than the other two. Neither Bush or Obama would agree to sending lethal aid to Ukraine. Trump did send arms. The perceived hesitation from Trump over arms shipments was from his apparent attempt at a quid pro quo to get information on the corruption of the Bidens during the Obama administration. It wasn't from fear things would escalate.
History has proved Trump's actions at arming the Ukrainians correct. That period was the only period in which Russia didn't invade one of its neighbors.
View: https://twitter.com/RonFilipkowski/status/1499055907099099153
Then Biden came in to office, okayed a "minor incursion" into Ukraine and now we have a lot of dead people. Thanks Joe!