Army counterintelligence officials in South Korea are investigating fake mobile alerts and social media messages warning American military families and Defense Department personnel of orders to evacuate the volatile peninsula on Thursday.

U.S. Forces Korea “did NOT send this message,” officials said in a subsequent Facebook post. They warned that Americans living in South Korea with U.S. troops and Defense Department employees should confirm that any evacuation-related communications are legitimate before acting.

“Anyone receiving this false message should not click any links or open any attachments included in the correspondence,” the Facebook message said.

The U.S. military did not indicate who it thought had sent the phony messages, and it is unclear whether any military networks were compromised. An advisory issued by the Army and reported by Stars and Stripes urged people who have received the message to report it to an Army counterintelligence unit, which assess attempts by adversaries and their foreign intelligence services to exploit or access U.S. networks.