The US State Department has called on American citizens around the world to exercise caution, particularly in the Middle East, in connection with heightened security threats. The corresponding warning was posted on the department's website.

"The State Department recommends that Americans worldwide, especially in the Middle East, exercise increased caution. Follow the guidance contained in security alerts issued by US embassies and consulates," the statement reads.

The department noted that several US diplomatic missions have already come under attack, including outside the Middle East. The State Department indicated that other institutions representing American interests may also be targeted.