In a Department of Homeland Security briefing Aug. 10, Robert Stephan, assistant secretary of homeland security for infrastructure, asked that emergency services agencies increase their vigilance and heighten security postures in their communities. The briefing was held in response to arrests of extremists plotting mass-casualty events in airplanes en route from the United Kingdom to the United States.

“Currently, there is no indication, however, of plotting within the United States,” said Stephan. “We believe that these arrests have significantly disrupted the threat, but we cannot be sure that the threat has been entirely eliminated or the plot completely thwarted.”

DHS is taking immediate steps to increase security measures in the aviation sector in coordination with heightened security precautions in the United Kingdom.

The U.S. emergency services sector was advised to maintain an increased state of alert in case there are unknown remnants of the United Kingdom-based plot and to guard against would-be copycats.