The Department of Homeland Security will soon begin issuing public advisories to provide information about developments in the terrorist threat, including suggestions about what people should do in response.

“We are in a new phase of global terrorist threats," Homeland Security Secretary Jeh Johnson told reporters on Wednesday during a press conference about the new public advisory system.

The announcement included the first “bulletin” informing Americans that while there is no new intelligence of a specific, credible threat, the public should remain vigilant. The bulletin will remain in effect until June 16th of next year.

“We know of no new intelligence that is specific or credible at this time, the reality is terrorism inspired individuals have conduced or attempted to conduct attacks in the U.S. this year,” Johnson said. “Recent attacks and attempted attacks warrant increased security, as well as increased public awareness.”

Homeland Security is especially worried about so-called "soft targets" such as public places that could be vulnerable to attack.

DHS is “especially concerned that terrorism inspired individuals and home grown individuals may be encouraged or inspired to target public places,” Johnson said. “Therefore the public should expect a heightened security and law enforcement presence at public places and events this holiday season.”

Johnson has long expressed a need to pass along information that does not meet the thresholds in the current National Terror Threat Advisory system.

NATIONAL TERRORISM ADVISORY SYSTEM: ** BULLETIN ** More information is available → https://t.co/UNbZJCgg8j pic.twitter.com/H2OgXYqWiq — Homeland Security (@DHSgov) December 16, 2015

The current system, launched in 2010, employs two levels — "elevated," to warn of a credible threat, and "imminent," to give notice of a specific impending threat. The system has not yet been used.

The new system is intended to communicate a level of information that allows people to be aware of what their government knows about potential threats, according to a senior Homeland Security official.

Wednesday's announcement adds a new "bulletin" level "to describe current developments or trends regarding terrorist threats, to outline actions the government is taking in response, and to give advice about what people should do to report suspicious behavior," the official said.

A bulletin might, for example, inform people to expect longer screening lines at public events at times and places when security is ramped up.

The new system was not devised in response to a specific or credible threat and has instead been in the planning stages for the past nine months, the official said.

Wednesday's announcement marks the third change in the system for informing the public of terror threats since the 9/11 attacks. The first used five colors to describe the threat picture, from low to severe. It was replaced with the two-level system by former Homeland Secretary Janet Napolitano.

David Heyman, a former Homeland Security policy official who advocated eliminating the color code system, welcomed the announcement.

"Given the current threat environment where we clearly understand the tactics of terrorists but have little to no notice of attacks, Secretary Johnson was looking for a way to formally communicate threat information to the public," Heyman said.

"The Secretary wanted a way to do that without raising the alert level, which historically has heightened fear without providing information about how to better protect ourselves, and without simply allowing information to come from leaked sources."