You (and rednecks in the USA) are asking whether the invasion of Ukraine would have happened under the former President who stated that Putin's invasion of Ukraine was "genius" and "wonderful".
Why on earth would you question whether a man who is supporting the invasion would have prevented it? The same man who was impeached for blackmailing the Ukrainian PM with withholding £400m of military aid.
Trump would be cheerleading from the Oval Office as the first Russian tanks crossed the border into Ukraine.