The Daily News has an exclusive op-ed from President Barack Obama on remembering the eighth anniversary of the September 11 attacks. The full op-ed is here, but here's an excerpt:

Eight years ago, on an ordinary Tuesday morning, nearly 3,000 lives were lost in the deadliest attack on American soil in our history.

It was an event that forever changed the life of this city. And it was a tragedy that will be forever seared in the consciousness of our nation.

Every year on this day, we are all New Yorkers.

We pause to remember the victims, to grieve with the families and friends of those who died, and to honor the heroes of that day and each day since who have sacrificed to save lives and serve their country.

We will never forget the images of planes vanishing into buildings; of billowing smoke rolling down the streets of Manhattan; of photos hung by the families of the missing.

We will never forget the rage and aching sadness we felt.

And we will never forget the feeling that we had lost something else: a sense of safety as we went about our daily lives.

The memory of those images and that vulnerability reminds us of the real and present danger posed by violent extremists who would use terrorism against Americans at home and around the world.

As President, my greatest responsibility is the security of the American people. It is the first thing I think about when I wake up in the morning. It's the last thing I think about when I go to sleep at night.

He goes on to discuss what he's trying to do to "reduce the likelihood of an attack" and also emphasize "why we are marking this Sept. 11 as a National Day of Service and Remembrance. On this day, and every day, it is incumbent on each of us to uphold those ideals that our enemies were - and are - so eager to destroy. To serve others and give back to our communities. To respect our differences and to value what we share. To remember that even when we disagree, and disagree strongly, that we are all Americans - that we are all striving to leave for our children a safer and more perfect union." Obama will be visiting the Pentagon today; Vice President Joe Biden is at Ground Zero.

The September 11 commemoration events are underway at Zuccotti Park and Ground Zero; you can see streaming coverage at NY1 and NBC New York.