American nationals registered with the U.S. Embassy in Turkey’s capital of Ankara were sent alerts via email and text messages warning of possible Islamic State group attacks on places of worship during the Easter holiday weekend. Citing local media reports, the embassy said Saturday Turkish authorities were stepping up security around churches and synagogues, as well as diplomatic missions.

“U.S. citizens are reminded to maintain situational awareness and the ability to communicate in an emergency,” the embassy said in its messages. “Keep a low profile, stay away from crowds and demonstrations and avoid becoming time and place predictable.”

No specific threats were mentioned. The U.S. Embassy was simply citing Turkish warnings, as opposed to issuing its own, its messages said.

Turkey has been on heightened alert amid a wave of recent terrorist attacks, including one in a busy shopping and tourist district. That attack, killing three Israelis and an Iranian, was reportedly linked to the militant group aka either ISIL or ISIS. And in that case, foreign nationals also were warned to be vigilant as the Kurdish-celebrated holiday of Nowruz approached. Germany temporarily closed its embassy and consulate for several days, citing credible security threats.

At least four bombings in Turkey during the past eight months have been linked to ISIS, which continues to control large swaths of land in Iraq and Syria. An attack in October targeted a pro-Kurdish rally, leaving more than 100 people dead.

Meanwhile, Turkey has also faced a parallel threat posed by Kurdish militants since a tenuous ceasefire between the two sides collapsed last summer. An offshoot of the Kurdistan Workers’ Party (PKK) claimed responsibility for an attack in Ankara this month that killed 37 people.

Police have warned ISIS could target consulates and embassies, as well as churches and synagogues in Ankara, Agence France-Presse reported. The growing instability caused by actual attacks and potential threats has driven away Turkey’s foreign tourists and hurt the country’s ability to attract long-term investments.