Democracy
If there is one thing that the USA has taught us, it is that democracy (US style) is always delivered via bombs and guns. So if that is true when democracy is being pushed on foreign countries, why should it not be the case in the USA also? Also, if its OK to manipulate elections in other countries to ensure they get leaders favourable to US interests, why would it be wrong to do the same in the US?
Good old America - reaping what it sows.