The U.S. virtual embassy in Iran issued a security alert on Friday, urging American citizens to leave the country and prepare an exit plan that does not rely on U.S. government help amid nationwide protests there.

The notice was issued just hours before U.S. and Iranian officials were scheduled to hold talks in Oman, amid mounting concerns about a possible military confrontation between the two countries.

“Today” show host Savannah Guthrie's brother on Thursday renewed the family's plea for their mother's kidnapper to contact them, hours after an Arizona sheriff said investigators don't have proof Nancy Guthrie is alive but believe “she's still out there.”

“Whoever is out there holding our mother, we want to hear from you. We haven’t heard anything directly,” Camron Guthrie said in a video posted on social media.