The U.S. State Department has asked Americans travelling abroad to remain vigilant in the wake of recent terror attacks in Paris and Mali. The State Department issued a worldwide travel alert on Monday, warning Americans of increased terrorist threats, according to the BBC.

"Authorities believe the likelihood of terror attacks will continue as members of ISIL/Da'esh return from Syria and Iraq. Additionally, there is a continuing threat from unaffiliated persons planning attacks inspired by major terrorist organizations but conducted on an individual basis," the department said in a statement.

The alert, which will expire on Feb. 24 next year, specifically asked U.S. citizens to excise caution during the holiday season. "Be aware of immediate surroundings and avoid large crowds or crowed places.  Exercise particular caution during the holiday season and at holiday festivals or events," it said.   

The department has not identified any specific threats, but warned that ISIL (Daesh), al-Qaeda, Boko Haram and other terrorist groups continue to plan terrorist attacks in multiple regions, according to the Independent.

"Extremists have targeted large sporting events, theatres, open markets, and aviation services.  In the past year, there have been multiple attacks in France, Nigeria, Denmark, Turkey, and Mali.  ISIL/Da'esh has claimed responsibility for the bombing of a Russian airliner in Egypt," the department said.   

The "unusual" global warning came nearly a year after the state department's previous worldwide travel alert in December of 2014, according to Press TV.