ORLANDO, Fla. (AP) – The Homeland Security is set to issue a new terror alert system bulletin that will highlight the threat environment facing the United States.

The bulletin will be effective Thursday, the same day a bulletin issued in December expires.

DHS Secretary Jeh Johnson announced in December the addition of bulletins to the National Terrorism Advisory System. At the time, he said the bulletin was being issued to keep the public informed in a “new phase off the global threat environment.”

That global threat environment, he says today, hasn’t changed and U.S. authorities remain worried about homegrown violent extremists “who could strike with little or no notice.”

A gunman attacked a nightclub early Sunday, leaving 49 people dead and wounding 53 others.