The US not only does not police the world to prevent dictatorships, it actively supports most of them through Foreign Military Financing, and openly trades with even more than those. Arguably, US foreign policy is one of the most significant factors in exacerbating international terrorism, in increasing insurrectionary violence, and in the increase of dictatorships and authoritarianism. US disengegement would end in fewer dictatorships, and likely a much more peaceful world.