Armed guards, safety assessments and now even a "Tactical Rabbi" to train volunteers on the use of weapons -- such is the reality today at synagogues in the United States facing mounting anti-Semitic attacks.

It is at a shooting range in the hills overlooking Los Angeles that a team of AFP reporters met recently with Raziel Cohen, dubbed the "Tactical Rabbi," who was sporting a 9mm pistol on his hip and carrying a semi-automatic rifle over his shoulder.

Cohen was trying to determine how well books can stop bullets.

The idea is to transform a library at a synagogue or Jewish school into a shelter in the event of an active shooter situation.

"We're trying to bridge the gap between the time that the shooting begins and law enforcement arrives," he told AFP.

"The expression that goes on is that we carry guns because we can't carry police officers, which is not just a joke," added Cohen.

"The reality is that there can't be police everywhere all the time."

Cohen, who has been passionate about guns since his youth, is a security expert and certified shooting instructor who has taken part in counter-terrorism courses given by retired and elite active-duty military personnel.

Born into a religious family, Cohen is also a rabbi for the Chabad-Lubavitch community in Los Angeles.

Chabad is a sect of Hasidic Judaism, and Los Angeles is second only to Brooklyn, New York in its number of Chabad congregations.

Cohen said his expertise in security took on more meaning after the April 27 shooting at the Chabad Poway Synagogue near San Diego that left one dead and three wounded.

It came six months after a shooting at a Pittsburgh synagogue left 11 people dead -- the worst attack against Jewish people in the modern history of the United States.