DHS extends a terrorism awareness bulletin that has been in place since 2015. Noting that:
“We continue to face one of the most challenging threat environments since 9/11, as foreign terrorist organizations exploit the Internet to inspire, enable, or direct individuals already here in the homeland to commit terrorist acts. Homegrown terror suspects increasingly rely on technology, such as end-to-end encrypted social media applications, to avoid detection.
Terrorist groups are urging recruits to adopt easy-to-use tools to target public places and events. Specific attack tactics have included the use of vehicle ramming, small arms, straight-edged blades or knives, homemade explosives, and poisons or toxins.
Some terrorist groups overseas are using battlefield experiences to pursue new technologies and tactics, such as unmanned aerial systems and chemical agents that could be used outside the conflict zones. Additionally, terrorists continue to target commercial aviation and air cargo, including with concealed explosives.
Violent extremist media encourages individuals worldwide to launch attacks using all means possible. Continued U.S. and partner successes in disrupting and defeating terrorists on the battlefield may encourage homegrown terrorists to carry out acts of violence in the homeland instead of attempting to travel overseas to fight or in retaliation for apparent losses.
Additionally, foreign terrorist fighters who have acquired training and battle-tested terrorism experience may flee from terrorist-controlled territories with a desire to conduct attacks elsewhere, including the United States.”