When most Americans hear the word "terrorism" they think of one thing: Big passenger planes slamming into the World Trade Center towers.

But the majority of you, as American law enforcement officers, will never find yourself in a struggle with a determined squad of al-Qaeda suicide bombers. That's terrorism with a capital "T."

No, it's more likely that you will face terrorism with a small "t." Some kid with visions of saving the planet will spray paint "ELF" (Earth Liberation Front) on some SUVs and firebomb a local car dealership. Neo-Nazis will vandalize your local synagogue. Pro-Life activists will attack a local Planned Parenthood center. An Islamist radical will gun down people in the street. These are examples of the kind of terrorism you are most likely to face. And make no mistake, these types of attacks can represent a deadly threat to you and the people you serve.

A lot of terrorism with a small "t" has been in the news lately.

H On May 31, Dr. George Tiller was murdered in the foyer of his Wichita, Kan., church. Tiller was director of a clinic that specialized in late term abortions. Anti-abortion activist Scott Roeder was charged with first-degree murder in the case.

H On June 1,  Islamist terrorism reared its ugly head in the most unlikely of places when a Muslim convert attacked two soldiers taking a smoke break outside of a Little Rock, Ark., recruiting center. Police say Abdulhakim Mujahid Muhammad (born Carlos Leon Bledsoe in Memphis, Tenn.) drove by the recruiting center and opened up on the soldiers with an SKS rifle. Pvt. William Long, 23, was killed. Pvt. Quinton Ezeagwula, 18, was wounded and hospitalized; he is expected to make a full recovery.

Muhammad was apprehended immediately after the shooting, and he thankfully didn't resist arrest. Police say he told them that he shot the two soldiers in retaliation for actions by the U.S. Army against Muslims. He reportedly said that he wanted to kill as many American soldiers as possible. Muhammad was charged with one count of first-degree murder and 15 counts of committing terrorism. I think he should have been charged with treason.

Authorities believe Muhammad was a lone gunman. But he just happened to be on the FBI's radar because he just returned from a pleasant vacation in Yemen. I'm going to go out on a limb here and say the FBI should arrest anyone who thinks going to Yemen is a pleasure trip; it shouldn't just put them on a watch list. The place is the poorest country in the Middle East so it has nothing to offer travelers, except terrorism training at the hands of rabid Islamists.

H On June 12, terrorism with a small "t" struck again in an old and familiar American form: The neo-Nazi, anti-Semite, racist bastard. That afternoon James W. Von Brun, an 88-year-old World War II veteran, allegedly attacked security officers at the U.S. Holocaust Memorial Museum in Washington, D.C.

Imagine an 88-year-old man so filled with hate that he wanted his last act on this planet to be gunning down a security guard at a museum dedicated to religious and racial tolerance. It boggles the mind. Von Brun was charged with murdering Stephen T. Johns, 39. Witnesses say Johns opened the door for the elderly Von Brun seconds before Von Brun opened fire. Von Brun was shot by other guards and is expected to survive to face trial.

I have recounted this litany of horrors to remind you of one thing: Terrorists walk among us. They don't all have long beards and turbans and live in caves in Afghanistan. Their acts of terrorism with a small "t" can happen anywhere in America. You need to be ready to face this threat, regardless of where you live and work.

Related:

Terrorism With a Small "t" (podcast)