A little girl I knew was on the plane that hit the Pentagon on 9/11. Her death changed the course of my life as America changed forever.

• An 8-year-old girl I knew on 9/11 was in the plane that hit the Pentagon.
• Her death and the deaths of nearly 3,000 people changed me, America, and the world forever.
• Two decades later, the US is still locked in a seemingly never-ending war.
• See more stories on Insider's business page.

I was 13 on 9/11, living in a Maryland suburb just outside of Washington, DC.

When the first plane hit the World Trade Center at 8:46 a.m., I was at school in homeroom. We went on lockdown not long after. It wasn't immediately clear what was happening. I wondered whether the US was being invaded.

My teacher, a typically jovial choir director, appeared as if he'd seen a ghost. He briefly left the classroom at one point, before returning to tell us that his bosses didn't want students to know what was going on. They didn't want to cause panic. But it was unfair to keep us in the dark, he said, and we were old enough to hear the truth. He told us that America was being attacked, and two planes had hit the World Trade Center. I couldn't begin to fathom what that meant, nor the massive consequences it would have for the wider world.

School ended early. The weather was beautiful, with the sky a piercing shade of blue, which felt wrong given the devastation that rained from above that day. I walked to a friend's house and we watched the footage of the planes hitting the towers on the news. It was haunting. It still is.

Eventually, I made my way home. In the hours that followed, a friend called to tell me that a little girl we knew was on the plane that hit the Pentagon - American Airlines Flight 77. Her family was en route to Australia when the plane was hijacked.

Her name was Zoe Falkenberg. She was 8-years-old.

-9/11 Memorial & Museum (@Sept11Memorial) November 8, 2016

I didn't know Zoe especially well. We were in a musical together at my elementary school - "Brigadoon" - when I was in 6th grade. I have memories of us playing and giggling, and running down the hallway of my school with her on my shoulders. But we weren't particularly close.

Her death still hit me like a brick. I cried myself to sleep that night, imagining how frightened she must've been as the plane was going down. An image of her terrified face replayed over and over in mind. My teenage brain could not comprehend why anyone would want to kill such a sweet, adorable little girl.

Before Zoe, I'd never known anyone younger than me who'd died. She was the first in that regard, and she was killed in the worst terror attack the US has ever seen. It was the beginning of my political awakening, and set me on the path toward becoming a reporter.

Growing up with the war on terror

Zoe's death, and the deaths of the 2,977 people who were killed that day, changed me, my country, and the world forever.

The US used those deaths as justification for launching an ongoing, global conflict - the so-called "war on terror" - that's killed up to 929,000 people (including over 7,000 US service members), displaced at least 37 million, and has an estimated price-tag of over $8 trillion. The war on terror has killed at least 387,072 civilians - roughly 129 times the number killed in New York City, Washington, DC, and Pennsylvania on September 11, 2001.

In the immediate aftermath of the attacks, I wanted the US to get revenge. I thought the terrorists responsible were pure evil and should be eradicated from the earth at all costs. Apparently, the White House and the vast majority of Congress - elected representatives meant to have steady, reasoned judgment in the face of crises - shared the same the sentiments of an emotional, ignorant 8th grader.

America responded to terrorism with its own versions of terror: torture, throwing people into Guantanamo without charges or trial, the unilateral invasion of Iraq in 2003 predicated on falsehoods, drone strikes. Many aspects of the US reaction to 9/11 violated the country's purported values as well as international law in profound ways. And jihadist groups have taken advantage of this, using the dubious actions of the US government as a recruiting poster for extremism.

9/11 ultimately exposed my generation to the ruthless extent of American militarism, and saw us grow up in a paranoid security state. Coming of age during the war on terror shattered the myths we'd been taught about our country.

By the time I reached college in 2006, I was utterly disenchanted with the US government. I felt lied to and betrayed - particularly over Iraq. The Bush administration had been adamant that Saddam Hussein's government was developing weapons of mass destruction and had close ties to Al Qaeda. None of it was true.

They exploited Zoe's death, and the deaths of all those who perished on 9/11, to start an illegal war that destabilized an entire region and made America an international pariah.

Then came Barack Obama. He pledged to move toward ending the war on terror. But just three days after he was inaugurated, the first drone strike of his presidency was conducted. His approach to terrorism was death from above.

As the drone strikes escalated, I had more and more questions. Why was it OK for the US to conduct strikes in countries with which it was not at war? How did we know the people killed were really terrorists? Was the government being honest about civilian casualties?

The notion 9/11 was being used to vindicate US operations that often ended up killing innocent people - including children like Zoe - infuriated me. I would end up writing my master's thesis on Obama's drone war, dissecting his administration's justification for the strikes and questioning whether they really made us more safe.

My anger over the war on terror is what morphed me into a journalist.

'Never forget'

A few days after 9/11, I walked to Zoe's house with a friend and laid flowers at her door. There was a makeshift vigil on the doorstep, filled with candles, notes, and pictures. The whole community was grieving. Zoe had died on that fateful flight alongside her sister Dana, 3, and parents Leslie Whittington and Charles Falkenberg.

We knew that the house was now empty and that eventually everything would be cleared away, but it was the best we could do in terms of holding a memorial under the circumstances.

I live in New York City these days. I've been here for seven years. On almost every anniversary of the attacks, I've headed to the 9/11 memorial in the financial district. I've made a point to find Zoe's name each time. I know exactly where it is. Every time I go, I see flashbacks of the flowers that were placed in front of her vacant house in September 2001.

Though she was only in my life for a brief moment, Zoe's been one of my greatest teachers.

She's taught me that grief is something you carry with you and it comes in many forms. She's taught me to never stop questioning what the government does abroad in our country's name. She's taught me that emotions can be exploited by those in power to do terrible things. And she's taught me that "never forget" should not just be about 9/11 itself, but everything the US government has done as a consequence of that horrible day.