Sen. Tammy Duckworth (D-Ill.) on Capitol Hill in February. (Alex Brandon/AP)

Tammy Duckworth, a Democrat, represents Illinois in the U.S. Senate.

Josephine Gay loved to spend her summers running her own lemonade stand.

Siretha White’s mother called her “Nugget” because she brought her family more joy than a nugget of gold.

Peter Wang had his heart set on serving his country in uniform one day.

Josephine was 7 when she was murdered at Sandy Hook Elementary School in Newtown, Conn. Siretha was 10 when she was gunned down at her birthday party in Chicago. Peter was 15 when he sacrificed his own life to help his classmates escape a shooter at a Parkland, Fla., high school.

This past week, as we mourned the anniversary of the Sandy Hook massacre, I couldn’t help but think about who these kids would’ve become if they’d been allowed to grow up — if they hadn’t lost their lives to gun violence before they’d even really started living.

Imagine your own little girl or boy being forced to stare down the barrel of a semiautomatic. Then imagine knowing that their death was preventable — if only it weren’t so easy for anyone to get their hands on weapons of war, including the AR-15s used in most mass shootings in recent memory.

I come from a long line of combat veterans who have taken up arms to defend this nation since before George Washington crossed the Delaware, and I spent decades in the military myself. So I understand why these kinds of weapons exist.

But what I don’t get is why semiautomatics that U.S. service members carry around Fallujah are being sold to teenagers at the corner gun store.

What I don’t understand is how some politicians can consider the National Rifle Association’s dollars more important than our kids’ lives.

Or how our streets have become deadlier than war zones, with more Americans killed by gun violence over the past 50 years than in every war in American history combined.

And what I can’t even begin to comprehend is how after Newtown and Charleston, Orlando and Las Vegas, Parkland and Pittsburgh, nothing has changed. You can still just walk into a gun show then leave a few minutes later with a weapon in hand — without undergoing a background check.

You’d never find such a casual approach to weapons in the military.

Instead, those who serve spend time learning the nuances of their rifles. They’re trained by drill sergeants until they’re so familiar with their weapons they could assemble them blindfolded. They take test after test.

Only then can troops graduate from basic training and begin to carry weapons that tear through skin as if it’s tissue paper.

There’s a reason, despite all their differences, Green Berets and teachers and lieutenants and parents marched side-by-side at last spring’s March for Our Lives.

It’s because each of them knows that something’s wrong when kids walk into school every morning unsure if they’re entering a combat zone.

We cannot become numb to this: This is murder — mass murder — that we’ve somehow simply accepted as the new norm.

Well, to hell with the status quo if that means our children could be murdered in art class.

I went to Iraq because I felt it my duty to be there. I chose to risk my life, to be shot at, to serve this country. These kids didn’t.

No child volunteers to have their neighborhood turned into a shooting gallery. But that’s what this country’s inaction on gun violence has allowed.

As long as we keep doing nothing, we’re complicit in Josephine’s death. In Siretha’s murder. In the fact that Peter never got to attend West Point like he dreamed.

There are ways to stem the bleeding. Common-sense bills we could pass that wouldn’t come close to infringing on anyone’s Second Amendment rights — like legislation to strengthen background checks that 97 percent of Americans support, including 91 percent of veterans and even most NRA members.

So from this one mom — this combat veteran, this marksman — please:

Tweeting out thoughts and prayers hours after another dozen people die isn’t good enough. We need to honor the victims not just with moments of silence, but also with action.

Because no one should kneel in their pew, sit down at their desk or dance on a Saturday night with the fear that every prayer, every lesson, every song could be their last.

No other school should be better known for the blood that was shed in its classrooms than the curriculum taught there.

No other place where our loved ones learn or play or pray should be turned into a war zone.

For goodness’ sake. It’s enough.