Beatrice Fihn used her speech to describe nuclear weapons as “a madman’s gun held permanently to our temple.” Speaking in the context of a situation where U.S. president Donald Trump and North Korean dictator Kim Jong-un have been taunting one another, she said: “The only rational course of action is to cease living under the conditions where our mutual destruction is only one impulsive tantrum away.”

“Will it be the end of nuclear weapons, or will it be the end of us?” Fihn asked.

Seismologists detected tremors on Saturday that could have been belated aftershocks from North Korea’s nuclear test in early September. The country also tested an intercontinental ballistic missile late last month that it claimed could reach the whole of the U.S. mainland.

Trump has repeatedly called Kim “Little Rocket Man,” while the North Koreans have repeatedly referred to the president as a “dotard.”

After Trump was elected, the Bulletin of the Atomic Scientists moved their Doomsday Clock closer to “midnight,” saying his election brought the world closer to the apocalypse due to Trump’s “casual talk about nuclear weapons,” as well as his environmental policies.

The “clock” now stands at two-and-a-half minutes to midnight, which is closer than it has been at any time since 1953.

Speaking on Sunday, Fihn said the risk of nuclear weapons being used was now greater than during the Cold War. ICAN, which is a coalition of smaller organizations, has long campaigned for a treaty that would ban the use of nuclear weapons.