The Federal Emergency Management Agency (FEMA) is updating emergency management plans to include plans for potential nuclear detonations in 60 U.S. cities.

An agency official told BuzzFeed News that the agency is shifting plans away from the likelihood of a terrorist detonating a smaller nuclear device and toward the possibility of a state actor detonating a military-grade nuclear weapon.

ADVERTISEMENT

“We are looking at 100 kiloton to 1,000 kiloton detonations,” FEMA chemical and nuclear branch chief Luis Garcia told BuzzFeed.

Experts told the website that the shift in policy was related to concerns over North Korea's nuclear weapons program, which some experts say has continued to develop despite President Trump Donald John TrumpSteele Dossier sub-source was subject of FBI counterintelligence probe Pelosi slams Trump executive order on pre-existing conditions: It 'isn't worth the paper it's signed on' Trump 'no longer angry' at Romney because of Supreme Court stance MORE and North Korean leader Kim Jong Un signing an agreement to work towards denuclearization.

The shift toward planning for actions by state militaries was discussed this week at a two-day workshop for public health and first responders at the National Academies of Science.

“The North Koreans have really changed the calculus,” said Cham Dallas of the Institute for Disaster Management at the workshop, according to BuzzFeed. “We really have to look at thermonuclear now.”

Other scenarios considered at the two-day meeting included responses to possible cyber warfare attacks and electromagnetic pulse attacks.

Concerns over Russian cyber intrusions have grown in recent months after it was revealed that Russian hackers gained unprecedented access to the control rooms of U.S. power plants.

“They got to the point where they could have thrown switches,” said Jonathan Homer, chief of industrial control system analysis for the Department of Homeland Security, earlier this year.

Russian hackers also targeted the campaign of Sen. Claire McCaskill Claire Conner McCaskillMomentum growing among Republicans for Supreme Court vote before Election Day Democratic-linked group runs ads in Kansas GOP Senate primary Trump mocked for low attendance at rally MORE (Mo.) a vulnerable Democrat up for reelection in November.

“Russia continues to engage in cyber warfare against our democracy,” McCaskill said in a statement last month. “I will continue to speak out and press to hold them accountable. While this attack was not successful, it is outrageous that they think they can get away with this. I will not be intimidated. I’ve said it before and I will say it again, [Russian President Vladimir] Putin is a thug and a bully.”