The US has a long tradition of tacitly supporting genocide, slaughter of civilians, collective punishment, torture and assassination or other extrajudicial murder of journalists and dissidents and labor leaders, mass surveillance, etc. etc. in places where “our dictator” happened to be in charge.
More directly, the US has directly toppled many democratically elected governments, undermined sovereign political processes via propaganda and support for anti-democratic political groups and targeted economic pressure, supported American and multinational corporations in their unethical and often criminal behavior around the world, given money and weapons and training to armed opponents of various democratic governments (who then used those for slaughtering civilians) ...
Not to mention being one of the world’s foremost producers and distributors of small arms (that end up in the hands of local gangsters, child soldiers, ...).
As a particularly tragic example, look to the case of Guatemala. The democratically elected president of Guatemala demanded that the United Fruit Company – who owned an incredibly high proportion of all arable land in the (starving) country – sell back some portion of the land which they were not currently using at the price it had been assessed to be worth for tax purposes. Unfortunately for Guatemala, the Dulles brothers (CIA director and Secretary of State), as well as various other members of the Eisenhower administration, had a direct business interest in United Fruit. The US toppled the government, installed a friendly dictator, and kicked off 2 generations of civil war in which a shockingly high proportion (5% or something?) of all Guatemalans were killed, including the mass-murder of many villages by thugs with machetes.
It is true that the presence of nuclear weapons has prevented for the past ~70 years the break-out of another “hot” war directly between nuclear-armed states. On the other hand, if someone slips up when nuclear weapons are involved, we’ll all be screwed.