In a travel advisory released Monday, the agency pointed to intelligence that suggests plans by terrorist groups such as the Islamic State in Iraq and Syria (ISIS), al-Qaeda and Boko Haram were in place targeting large sporting events, theatres, open markets and aviation services.

“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,” said the travel advisory.

This travel warning follows a spate of attacks across the world for which radical Islamic militant groups have claimed responsibility. Police are still hunting down ISIS-related suspects involved in the terrorist shootings in Paris, where at least 130 were killed in coordinated attacks across the French capital on Nov. 13.

This after Kremlin authorities determined that a bomb had brought down Metrojet Flight 9268 on October 31, killing 224 people on board. ISIS has also claimed responsibility for the attacks, saying a self-made “Schweppes” bomb took the plane down mid-flight.

On Friday, a siege on the Radisson Blu Hotel in Bamako, Mali, left 20 people dead. A North African armed group called Al-Mourabitoun, working in tandem with Al-Qaeda in the Islamic Maghreb, has claimed responsibility for the attack, according to Reuters.

U.S. citizens are warned to exercise vigilance “when in public places or using transportation”, and especially during the holiday season. The travel alert expires on February 24, 2016.