The FBI warned members of the U.S. military that ISIS is calling for attacks against them, according to a law enforcement source, saying that “overseas based individuals are looking for like-minded individuals in the U.S. to carry out these attacks.”

“We also request members of the military review their online social media presence for any information that might attract the attention of violent extremists,” the bulletin said, advising that members of the military “use caution and practice operational security when posting.”

The new FBI bulletin includes a concern that ISIS members are “spotting and assessing” individuals in the U.S. who they believe may be interested in carrying out attacks on U.S. soil against members of the U.S. military, a U.S. counter-terror official tells CNN.

The bulletin language warns of “individuals overseas spotting and assessing” individuals in the U.S., based on their social media postings in support of the group. The warning encourages members of the military to “exercise operational security” in response to such threats, including reviewing their online social media postings so as not to make themselves easier targets.

U.S. law enforcement posted the warning now in advance of the upcoming holiday season when many members of the U.S. military travel in uniform. The new warning also cites several recent attacks in Canada against members of the Canadian military, including the Oct. 22 Ottawa shooting and two other attacks using cars.

The concern in the FBI and intelligence community is that ISIS members overseas are tracking personal information about “specific” U.S. soldiers — such as their addresses and even their relatives addresses — based on their social media posts, according to a law enforcement official briefed on the matter.

The concern is that ISIS operatives are gathering it overseas and then identifying homegrown violent extremists in the U.S who could help carry out the attack. The source says the idea is basically ” I don’t have to come and get him — I can call someone in the U.S. who wants to support the cause and they can do it.”

A Pentagon spokesman said Monday morning that the bulletin “reinforces the guidance our combat commanders put out several weeks ago. This is nothing new for us.” Col. Steve Warren, the Pentagon spokesman, said he was “aware of no new intelligence” that led to the bulletin being sent.

The FBI also issued a security bulletin in October warning of similar attacks on U.S. soil against law enforcement personnel and members of the news media.

Terrorism and security experts have expressed growing concerns in recent months that ISIS could inspire individuals in the West to carry out terrorist attacks.

Australian authorities in September foiled an ISIS-inspired plot to kidnap and publicly behead someone in public.