Since 9/11, the United States has been devoting much of its blood and treasure to fighting a war against foreign terrorists. New agencies have been established, new funding has been appropriated, and law e­nforcement and military resources have been organized and tasked with stopping terrorist attacks.

But there's another war that's been raging since the Reagan years, a war that's recently been all but ignored by the American public. And like the war against jihadism and militant Islamists that had really been going on for more than 20 years before the 9/11 atrocities, turning a blind eye won't make the problem go away, it'll only make it worse.

What I'm talking about is the war against heavily armed, nihilist children: gangs. This is a war that every law enforcement officer should take very seriously because you are its foot soldiers. And you are taking serious casualties.

During the 30 days of April, three California officers-Highway Patrol Officer Thomas Steiner, Merced Police Department Officer Stephan Gray, and San Francisco Police Officer Isaac Espinoza-were all gunned down by what police say are gangbangers or gangbanger wannabes. In California, the bangers have gone on the offensive, and they will now kill cops without any concern for the consequences.

Consider the murder of CHP officer Steiner. Authorities say that on April 21, Valentino Mitchell Arenas, 16, waited near the South Pomona Courthouse for any law enforcement officer to walk by, saw Steiner, and shot him to death.

Any outdoor enthusiast will recognize exactly what Arenas is accused of doing. He's charged with setting up a stand in an area where he knew his desired prey would travel, biding his time until a target arrived, and then executing the kill. He's charged with hunting a cop.

Investigators contend that Arenas gunned down Steiner to curry the favor of Pomona's largest criminal organization, the 12th Street gang, sometimes known as the Sharkys. There's no word from the Sharkys, a Mexican Mafia affiliate, as to whether or not they approve. But one thing is certain: If Arenas did ambush Steiner and if he did so to gain a rep, then he succeeded.

Arenas is being tried as an adult but, even though the good citizens of the Golden State long ago decided that capping a cop should be a "special circumstance" and therefore eligible for capital punishment, the same citizens are squeamish about giving a high school kid the needle. So, if convicted, Arenas will spend the next 60 or 70 years as a "cop killer," a celebrity among the inmates in San Quentin.

Still, you gotta' give the Pomona prosecutors their due; they are seeking the maximum in the Steiner case. They know that you are at war and you need their support.

The same can't be said for San Francisco District Attorney Kamala Harris. Just three days after the slaying of SFPD officer Isaac Espinoza, Harris announced that she would not seek the death penalty for David Hill, 21, a reputed member of the Westmob gang who was charged with blowing away Espinoza with an AK-47. You see, Harris philosophically opposes giving cop killers the needle, a stance that's very popular among some area voters.

Of course, it's not so popular with local law enforcement. Police Chief Heather Fong and a number of other ranking SFPD officers have protested the DA's decision, saying Espinoza has been denied justice. But rank-and-file SF cops know what Harris has really done; she's painted even larger targets on their foreheads.

After all, the death penalty may not be an effective deterrent but it's the only real leverage that the good guys have against hardened gangbangers and their ilk who see prison as a party. With the death penalty off the table in San Francisco, veteran cops say gang members have become more bold, taunting local badge carriers with calls of "I got an AK-47 for you."

The message is clear. Thanks to Harris and others who have no clue what's at stake in the war against gangs, it's open season on cops in California.