May 16 (UPI) -- The Department of Homeland Security has renewed a bulletin warning of the "most serious" environment for homegrown terror threats since the 9/11 attacks.
"Foreign terrorist organizations continue to exploit the Internet to inspire, enable, or direct individuals already here in the homeland to commit terrorist acts," said the bulletin, issued late Monday through the National Terrorism Advisory System. "As the United States steps up efforts to disrupt and defeat terrorist groups overseas, we will continue to face a multi-faceted threat environment."
An NTAS bulletin was first issued in December 2015 to "highlight the continuing threat from homegrown terrorists." The bulletin has been renewed three times.
Monday's bulletin, which is set to expire in November, includes new warnings on terrorist techniques.
"Homegrown terror suspects are increasingly relying on technology, such as end-to-end encrypted social media applications, to avoid detection," the bulletin said. "Moreover, 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, and homemade explosives, as well as other acts such as taking hostages."
Homeland Security Secretary John Kelly said his decision to renew the bulletin came "after careful consideration of the current threat environment and input from intelligence and law enforcement partners."
Speaking at an event at the University of Chicago on Tuesday, Kelly said strong community networks can prevent radicalization.
"There's very few people that actually get radicalized," he said. "As an American society, we have families, we have friends, we have churches, we have mosques and synagogues, we have community this and that, we have police and all, we have a great country -- problems for sure, but we have a great country. And all of that works to keep people from becoming a white supremacist or radicalized or something like that."
Earlier this month, the State Department issued a travel alert urging citizens going to Europe this summer to be extra vigilant to the continued threat of terrorist attacks.