The note also asks Guam's residents to "take time to talk" to family members or co-workers who might be troubled after North Korea vowed to ignite an "enveloping fire" of test missiles near the island, which is a US territory.
"Most people that live here, they've heard this before", said Aaron Burger, who's lived here more than a decade.
The KPA spokesman said the Minuteman ICBM test-launch and the mobilization of "nuclear strategic bombers" from Guam indicated that the US was "driving the regional situation to an extreme pitch".
"I'm a little anxious, a little panicked".
Having experienced a Japanese invasion in World War Two and countless earthquakes and super-typhoons, there was no U.S. community better prepared than Guam "for any contingency", Calvo said. "If it's just me, I don't mind, but I have to worry about my son".
There were no signs of panic or an exodus from the island of 163,000 people on Thursday, with its wide roads clogged with commuters and commercial vehicles.
More recently, North Korean missiles have landed in the Sea of Japan, with some falling in Japan's exclusive economic zone that stretches as much as 200 nautical miles from its shores.
The escalating rhetoric raised concerns that any miscalculation could trigger a catastrophe.
National Intelligence Director Dan Coats told Congress in May that Kim has been photographed beside a nuclear warhead design and missile airframes to show that North Korea has warheads small enough to fit on a missile. An air base with long-range bombers and a naval base that's home port for fast-attack submarines are among the most "strategically important" the US has in the Pacific, according to the CIA World Factbook.
In response, Trump on Tuesday threatened the communist country "with fire and fury".
Homeland Security in Guam said on Friday that a public warning system in place that would alert residents of the island of 160,000 people that a missile is incoming.
On his flight back to Washington, Tillerson said he never considered re-routing the trip to avoid refueling in Guam. "The South Korea and USA governments are preparing for additional provocations from North Korea and watching related movements closely", Baik said.
Because Guam is a USA territory, the US military may launch forces from there without worrying about upsetting a host nation that may object to US actions.
McCain says he takes exception to Trump's comments "because you got to be sure you can do what you say you're going to do". "We have a lot of firepower, more than he has, times 20 - but we don't want to use it".
Other residents are anxious about the political atmosphere and the government's ability to find a peaceful solution.
At a church in central Guam on Sunday, parishioners sang "Lord, we pray for world peace" after discussing the potential North Korean threat.
"It was no accident that North Korea threatened to launch four missiles, it deliberately complicates the decisions of USA policy makers", he said. That is close to half the distance between Guam and Hawaii, which sits about 3,960 miles away.
Baumgartner, a supervisor at a high-end clothing store, said she was confident United States forces on the island's two bases were ready to intervene, and she bore no grudges about that military presence making Guam a North Korean target.
In August previous year, the North's Foreign Ministry warned that all USA military bases in the Pacific including Guam would "face ruin in the face of all-out and substantial attack" by the North's military. They say those plans will be ready within days and presented to leader Kim Jong Un to await his order.
Aegis is able to track 100 missiles simultaneously and fire interceptors to take out an enemy's ballistic projectiles.
Abella's statement came after North Korea announced a detailed plan to launch a salvo of ballistic missiles toward Guam, a major military hub and home to USA bombers, a move that if carried out would be its most provocative missile launch to date. "And we should be prepared too".
Following the North Korea threat, Governor Eddie Baza Calvo said he was in touch with the White House and told residents "there is no threat to our island or the Marianas". But they say the behind-the-scenes discussions could still be a foundation for more serious negotiation.