WATCH: Los Angeles suburb released this ominous video about how to survive a nuclear attack

Earlier this week, an analysis from US intelligence officials revealed that North Korea has figured out how to fit nuclear warheads on missiles, and that the country may have up to 60 nuclear weapons. (Some independent experts estimate the figure is much smaller).

On Monday, North Korea issued a stark warning to the US: If you attack us, we will retaliate with nuclear weapons.

Several American cities, including New York, San Francisco, and Honolulu, have response plans for terrorist attacks, including so-called "dirty bombs" containing radioactive material. But few have publicized plans to deal with a real nuclear explosion.

RELATED: A look at North Korea's July 2017 missile test

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A look at North Korea's July 2017 missile test
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A look at North Korea's July 2017 missile test
North Korean leader Kim Jong Un guides the second test-fire of intercontinental ballistic missile (ICBM) Hwasong-14 in this undated picture provided by KCNA in Pyongyang on July 29, 2017. KCNA via Reuters ATTENTION EDITORS - THIS IMAGE WAS PROVIDED BY A THIRD PARTY. REUTERS IS UNABLE TO INDEPENDENTLY VERIFY THIS IMAGE. SOUTH KOREA OUT. NO THIRD PARTY SALES. NOT FOR USE BY REUTERS THIRD PARTY DISTRIBUTORS.� TPX IMAGES OF THE DAY
Intercontinental ballistic missile (ICBM) Hwasong-14 is pictured during its second test-fire in this undated picture provided by KCNA in Pyongyang on July 29, 2017. KCNA via Reuters ATTENTION EDITORS - THIS IMAGE WAS PROVIDED BY A THIRD PARTY. REUTERS IS UNABLE TO INDEPENDENTLY VERIFY THIS IMAGE. SOUTH KOREA OUT. NO THIRD PARTY SALES. NOT FOR USE BY REUTERS THIRD PARTY DISTRIBUTORS.� TPX IMAGES OF THE DAY
People watch news report showing North Korea's Hwasong-14 missile launch on electronic screen at Pyongyang station, North Korea in this photo taken by Kyodo on July 29, 2017. Mandatory credit Kyodo/via REUTERS ATTENTION EDITORS - THIS IMAGE WAS PROVIDED BY A THIRD PARTY. MANDATORY CREDIT. JAPAN OUT. NO COMMERCIAL OR EDITORIAL SALES IN JAPAN.
The Central Committee and the Central Military Commission of the Workers' Party of Korea hold a banquet at the Mokran House in celebration of the second successful test-fire of intercontinental ballistic missiles (ICBM) Hwasong-14, in this undated picture provided by KCNA in Pyongyang on July 30, 2017. KCNA/via Reuters ATTENTION EDITORS - THIS IMAGE WAS PROVIDED BY A THIRD PARTY. REUTERS IS UNABLE TO INDEPENDENTLY VERIFY THIS IMAGE. SOUTH KOREA OUT. NO THIRD PARTY SALES. NOT FOR USE BY REUTERS THIRD PARTY DISTRIBUTORS.
The Central Committee and the Central Military Commission of the Workers' Party of Korea hold a banquet at the Mokran House in celebration of the second successful test-fire of intercontinental ballistic missiles (ICBM) Hwasong-14, in this undated picture provided by KCNA in Pyongyang on July 30, 2017. KCNA/via Reuters ATTENTION EDITORS - THIS IMAGE WAS PROVIDED BY A THIRD PARTY. REUTERS IS UNABLE TO INDEPENDENTLY VERIFY THIS IMAGE. SOUTH KOREA OUT. NO THIRD PARTY SALES. NOT FOR USE BY REUTERS THIRD PARTY DISTRIBUTORS.
Coverage of an ICBM missile test is displayed on a screen in a public square in Pyongyang on July 29, 2017. Kim Jong-Un boasted of North Korea's ability to strike any target in the US after a second ICBM test that weapons experts said on July 29 could even bring New York into range - in a potent challenge to President Donald Trump. / AFP PHOTO / Kim Won-Jin (Photo credit should read KIM WON-JIN/AFP/Getty Images)
A man and woman watch coverage of an ICBM missile test displayed on a screen in a public square in Pyongyang on July 29, 2017. Kim Jong-Un boasted of North Korea's ability to strike any target in the US after a second ICBM test that weapons experts said on July 29 could even bring New York into range - in a potent challenge to President Donald Trump. / AFP PHOTO / Kim Won-Jin (Photo credit should read KIM WON-JIN/AFP/Getty Images)
In this photo taken on July 29, 2017, a woman holding a mock rifle stands at a bus stop in Pyongyang. North Korea said July 30 its latest ICBM test was a 'warning' targeting the US for its efforts to slap new sanctions on Pyongyang and threatened a counter-strike if provoked militarily by Washington. / AFP PHOTO / Ed JONES (Photo credit should read ED JONES/AFP/Getty Images)
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One exception is Ventura County, a suburb about 60 miles northwest of Los Angeles. In 2003, the local government launched a PSA campaign called "Ready" that aims to educate Americans how to survive a nuclear attack. The goal, according to the campaign site, is to "increase the level of basic preparedness across the nation."

One of the more recent PSA videos is the one below, published in 2014. It opens with a short message from Ventura County public health officer Dr. Robert Levin, then cuts to a little girl with an ominous expression around the one-minute mark.

"Mom, I know you care about me," she says. "When I was five, you taught me how to stop, drop, and roll ... But what if something bigger happens?" The video then flashes to the girl walking down empty streets alone.

The Ventura County Health Care Agency has published severalguides on what to do in the event of a nuclear bomb hitting the area. As the girl says in the video above, the agency's focus is to "go in, stay in, tune in."

The scenario assumes a terrorist-caused nuclear blast of about 10 kilotons' worth of TNT or less. Few people would survive within the immediate damage zone, which may extend up to one or two miles wide, but those outside would have a chance.

Brooke Buddemeier, a health physicist and radiation expert at Lawrence Livermore National Laboratory, previously told Business Insider that he likes Ventura County's PSAs because they're simple and easy to remember. "There is a ton of guidance and information out there," he said, but "it's kind of too hard to digest quickly."

Buddemeier said you'd have about 15 minutes — maybe a little bit longer, depending on how far away you are from the blast site — to get to the center of a building to avoid devastating exposure to radioactive fallout. Going below-ground is even better.

"Stay in, 12 to 24 hours, and tune in — try to use whatever communication tools you have. We're getting better about being able to broadcast messages to cell phones, certainly the hand-cranked radio is a good idea — your car radio, if you're in a parking garage with your car," he said.

apartment building house radioactive fallout shelter protection quality level llnl brooke buddemeierBrooke Buddemeier/Lawrence Livermore National Laboratory

Buddemeier adds, however, that you shouldn't try to drive away or stay in your car for very long, because it can't really protect you. Today's vehicles are made of glass and very light metals, and offer almost no shielding from damaging radiation.

In large cities, hundreds of thousands of people would be at risk of potentially deadly exposure. But fallout casualties are preventable, Buddemeier said.

"All of those hundreds of thousands of people could prevent that exposure that would make them sick by sheltering. So, this has a huge impact: Knowing what to do after an event like this can literally save hundreds of thousands of people from radiation illness or fatalities," he said.

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