Beatrice Fihn said people could choose to ditch nuclear weapons or life.
The practice sessions come after North Korea slammed Trump as a "mentally deranged dotard" on Saturday.
There may be a psychological explanation for why the world is not more worried about possible nuclear warfare.
The converted Cold War–era silo housed an intercontinental ballistic missile with a warhead 32 times more powerful than what the United States dropped on Hiroshima.
North Korea is using video games to teach kids how to assassinate Americans at a propaganda camp.
Nibiru is not going to destroy the world, and these three possibilities are not likely to either.
North Korea has backed communist insurgencies around the world, but never to the extent in which the U.S. was involved in global conflicts.
Are Kim Jong Un's weapons more powerful than Trump's?
Kerry warns of "the risk of tweeting yourself or insulting yourself into a position where something happens"
"The thing that scares me the most in the long term is the state of our politics here, and...it's gotten worse," Michael Morell said.
Leaflets from North Korea typically contain anti-American content but the latest wave are aimed specifically at Trump
On Iran, William Perry is clear: "If the deal were abandoned...Iran will resume the nuclear program they had before."
The sale of $113 million worth of advanced air-to-air missiles to Japan needs to be approved by Congress.
New analysis uses North Korea's estimated capabilities to calculate the amount of casualties that would result from a nuclear attack.
The Plutocene would be characterised by extremely high global temperatures, leading to "mega-cyclones, mega-floods and super-tropical terrestrial environments."
More sanctions will not curb North Korea's ambitions, Russia's deputy foreign minister said, but a U.S. military response will not do it either.
Starting a nuclear war really would bring "fire and fury like the world has never seen."
Tillerson said "Americans should sleep well at night" after President Trump leveled "fire and fury" threat at North Korea.
The president said nuclear threats from North Korea would be met with "fire and fury."