Some U.S. military personnel or their families stationed in South Korea received fake messages claiming they had to evacuate immediately, military officials confirmed.

The hoax was sent out Thursday to mobile phones and Facebook accounts of multiple U.S. servicemembers or their families. The message said an order for a noncombatant evacuation operation (NEO) has been issued.

“On Thursday, 21 September 2017, multiple reports indicated a fake NEO alert had been issued to multiple servicemembers and spouses in the Republic of Korea,” read a message posted Thursday on the 8th Army’s Facebook page.

The official page of U.S. Forces Korea also confirmed the notice, writing on Facebook: “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.”

A noncombatant evacuation operation (NEO) would affect the family members of the 28,500 U.S. servicemembers stationed in the Korean Peninsula and other non-emergency employees of the Defense Department, Stars and Stripes reported.

The military performs biannual evacuation drills, but none have been issued since the end of the Korean War more than 60 years ago.

The army’s military message emphasized that it did not issue any evacuation orders, writing “USFK did NOT issue this message” and urged personnel and their family members to exercise vigilance.

“Do not accept information from unconfirmed sources,” the Army wrote. “Do not click any links or open any attachments included in unexpected correspondence.”

USFK spokesman Chad Carroll told Stars and Stripes that the false alerts were reported within an hour and only a “handful of servicemembers and families” received them. The fake messages are being investigated by cyber personnel.

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

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

The hoax comes in the wake of increased tension between in the region as North Korea continues to escalate by showcasing its progress in the nuclear weapons program.

The North Korean regime has conducted at least three nuclear tests since last year and has fired multiple missiles, including two that flew over Japan.

President Donald Trump said Tuesday that he would “totally destroy” the rogue country led by “Rocket Man” Kim Jong Un if the U.S. is forced to defend its allies or itself.

In response, the North Korean leader said Trump was “deranged” and would ultimately regret issuing the threat.