(AP) -- The U.S. updated its terror alert system on Wednesday, unveiling a new "bulletin" category intended to better inform the public about evolving terrorist threats.

Homeland Security Secretary Jeh Johnson said there remains no credible, specific terror threat to the United States but that the department nevertheless issued its first bulletin to keep the public informed in a "new phase of the global threat environment."

Wednesday's bulletin will be in effect until June 16, 2016 and outlines much of what Johnson and other federal have said in the days and weeks since the attacks in Paris and San Bernardino.

Johnson reiterated that while there's no specific threat, the government remains concerned about terrorist-inspired extremists, such as the attackers in California who killed 14 people before dying in a shootout with police.

The bulletin joins two other existing alert categories, elevated and imminent. An elevated alert warns of "a credible terrorism threat" while an imminent alert advises the public of a "credible, specific and impending terrorism threat."

This is the first change to the National Terrorism Advisory System since it replaced the color-coded system in 2011.

Johnson said administration officials considered issuing an alert earlier this year but decided that there was not enough specific information to meet the threshold do so.

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