It's hard to tell what Reagan would have done since he was profoundly ignorant of the relatively primitive computer technology of his era, I am pretty sure he would issue ultimatums of massive retaliation and you would love him for it. He also would not be Russian sympathizer like so much of Trump crowd seems to be.
Please ...........Your talking point of us being sympathizers is just that....wasnt it Obama who told russians to be patient ,,,,after his last election he would have more leeway to cooperate