The State Department warned U.S. citizens on Friday against traveling to southeastern Tunisia near the Libyan border.

The warning, which is more serious than the travel alert issued a month ago, comes after groups affiliated with ISIS militants have targeted Tunisian security forces and tourist sites in the region.

It calls for U.S. citizens to avoid traveling near the Libyan border or the mountainous areas of western Tunisia and to be vigilant in all places in Tunisia frequented by tourists. The country’s tourism revenue has plunged.

U.S. citizens are urged to avoid Tunisian political gatherings, large crowds and demonstrations and to be alert to the possibility of kidnapping, the warning said.

Last year, ISIS militants perpetrated two major attacks in Tunisia that killed dozens of foreigners.

On March 22, President Beji Caid Essebsi renewed Tunisia’s state of emergency, which was put into effect after last year’s attacks, extending it three months until June 22.

“Travelers contemplating trips to the interior of Tunisia should assess local conditions and routes when making travel plans,” the State Department warned. “In particular, all travel south of the designated military zone in the south must be coordinated in advance with Tunisian authorities.”