The last time the State Department issued such a warning was in 2003.
The State Department issued a " target="_blank"worldwide caution" warning hours after President Donald Trump's announcement on Wednesday that the US would recognize Jerusalem as Israel's capital and move the American embassy there.
"U.S. government facilities worldwide remain in a heightened state of alert," the warning read. "These facilities may temporarily close or periodically suspend public services to assess their security posture. In those instances, U.S. embassies and consulates will make every effort to provide emergency services to U.S. citizens."
The warning went on to urge American citizens to be aware of local developments and remain in contact with US embassies or consulates.
As Matt Lee, a diplomatic reporter for the Associated Press, noted on Twitter, such a warning was issued in 2003 after the start of the Iraq War when the State Department believed an attack against US citizens by Al Qaeda was imminent.
Protest and skirmishes erupted on Thursday in the West Bank and the Gaza Strip where the Palestinian Authority has called for general strikes. Hamas, the Palestinian Islamist group that both Israel and the US consider a terrorist group, has called for a third intifada, or uprising, against Israel.
In response to potential threats, US embassies across the Middle East have strengthened security measures, and remain on high alert.
But compared to previous instances of mass outrage against Israel, the overall response was not as explosive as had been expected, according to The New York Times. As other regional crises like the Arab Spring, ISIS, and the Syrian civil war have taken center stage, the fight for a Palestinian state has not continued to be as powerful a rallying cry as it once was.