"For the first time in history, nuclear weapons are going to be illegal in international law," says Elayne Whyte, who oversaw the treaty's creation.

Kim's comments come just days ahead of President-elect Joe Biden's inauguration. Biden has promised "principled diplomacy" with North Korea, implying a break with Trump's high-stakes summits.

In the midst of a pandemic that's wreaking havoc on prisons and disproportionately affects older people, activists known as the Kings Bay Plowshares have been sentenced to up to 33 months in prison.

The bombings of Hiroshima and Nagasaki were said at the time to be justified as the only way to end World War II. Seventy-five years later, legal experts say they would now be war crimes.