The Pentagon announced Friday that it would be launching an investigation into a series of fake messages sent to US soldiers stationed in South Korea and their family members on Thursday. In what probably sent a temporary chill down the spines of recipients, the messages warned that all "non-essential" (i.e. non-combat) personnel must evacuate the Korean Peninusla - suggesting that the long-dormant Korean War was about to explode once again into violence, Reuters reports.

The hoax, which was spread via fake SMS messages and Facebook posts, was carried out during a particularly tense period in the ongoing standoff between the US and North Korea over the latter's insistence on developing a nuclear weapon capable of striking the US. Also on Thursday, the North's foreign minister warned that the regime was considering a test of a nuclear weapon over the Pacific – something that would represent an unprecedented escalation and possibly force the US to respond with a military strike. A military spokesman said there was no way of knowing how many soldiers or family members received the messages, but said the chain of command quickly acted to shut down the hoax.

“We have no accurate way to know how many people received it,” the spokesman said. “Incidents were ‘self-reported’ and many people claimed the message disappeared as soon as they unlocked their phone.”

The spokesman added that the “good news here” is that the hoaxer's attempt to create an outbreak of chaos was foiled.

“The good news here is: informed, savvy family members plus an engaged chain of command means no panic or over-reaction,” he added. “We had no reports of anyone acting on message other than notifying the appropriate authorities.”

Stars and Stripes reports that the hoax was reported by soldiers less than an hour after the alerts were sent. The hoax was spread via fake text messages and Facebook posts, the military said.

The USFK posted a statement on its official Facebook page on Thursday making clear that the US military did not issue any evacuation-related alerts. It has also instructed all US Department of Defense personnel and their family to confirm any evacuation-related communications before acting.

The notice alerted soldiers and their family members that the USFK did NOT issue the alert: “On Thursday, 21 SEP, we received multiple reports of a fake text-to-cell and social media message regarding a “real world noncombatant evacuation operation (NEO) order issued” which instructed DOD family members and non-emergency essential DOD civilians on the Korean peninsula that an evacuation order had been issued.”

Warnings were also posted on the 8th Army’s official Facebook page.

As Stars and Stripes explains, the messages referred to what is known as a noncombatant evacuation operation, or NEO, which would affect family members of the 28,500 U.S. servicemembers stationed in South Korea and non-emergency essential Defense Department civilian employees. According to Reuters, the USFK holds biannual NEOs to prepare soldiers and their families for just such an eventuality.

