The fact sheets did not seem to cause any widespread anxiety or affect day-to-day Guam life.
Officials have not raised the USA territory's threat level after Pyongyang said it had laid out plans to strike near the island in the coming weeks.
North Korea says it is in the final stages of preparing a plan to launch four intermediate-range ballistic missiles over Japan and into waters off the tiny island of Guam, where about 7,000 USA troops are based and 160,000 US civilians live.
The fact sheet, first reported Friday by the Pacific Daily News, explains that brick or concrete structures are the safest places to shelter from nuclear fallout, and that those with thick walls and roofs best absorb radioactive particles.
With North Korea threatening to send a salvo of ballistic missiles close to Guam, a USA military hub in the Pacific, pressure could grow for Washington to put its multibillion-dollar missile defense system into use and shoot them out of the air.
The fact sheet's title: "In Case of Emergency - Preparing for Imminent Missile Threat". Lying flat on the ground while covering your head would also be a sensible decision if caught outside, the document reads, as "it could take 30 seconds or more for the blast wave to hit". Radioactive material can spread, which is why removing clothing is vital. Instead, parents must wait for instructions to pick up their children from school, as every school has "emergency cards that identify who can pick up your child".
Still, Dee Cruz, a senior watch officer with Guam Homeland Security, concedes that "folks here are concerned because there's a lot of talk about it" - alluding to extensive media coverage of the public statements made by Trump and his counterpart in North Korea, Kim Jong Un.
Guam is home to a U.S. air base, a Navy installation, a Coast Guard group and roughly 6,000 U.S. military personnel.