Every year on this day, we are all New Yorkers - US President Barack Obama on 9/11 anniversary US President Obama sends a message of hope to all New Yorkers. 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. That responsibility is the heart of the policies my administration has put in place. No one can guarantee that there will never be another attack; but what I can guarantee - what I can promise - is that we will do everything within our power to reduce the likelihood of an attack, and that I will not hesitate to do what it takes to defend America. That is why we are providing the necessary resources and strategies to take the fight to the extremists who attacked us on 9/11 and who have found safe haven in Pakistan and Afghanistan. We are investing in the 21st century military and intelligence capabilities that will allow us to stay one step ahead of our enemies, including increasing the size of the Army and Marine Corps. And we have renewed our commitment to non-proliferation to prevent deadly weapons from falling into the hands of terrorists, launching an effort to secure all loose nuclear weapons and material around the world within four years. We are also better protecting our border and increasing our preparedness for any future attack or natural disaster. We are building new partnerships around the world to disrupt, dismantle, and defeat Al Qaeda and its allies. We have renewed American diplomacy so that we can once again lead the world to meet the threats we face. And in the policies and principles that guide our efforts, we are reaffirming a simple truth: that our strength as a nation comes not only from the might of our military, but also the power of our fundamental values. Indeed, amid the carnage and heartbreak of that tragic day in September, we also experienced a profound sense of community and witnessed a vivid display of those values, as first responders raced toward chaos, as Americans lined up to donate blood, as young people signed up to serve their country - as old divides seemed to fade away and America stood as one. Now, eight years later, it is that sense of common purpose we must recapture. That begins by remaining vigilant, by putting in place the policies that will best protect our security, by ensuring access to monitoring and treatment for the rescuers, as well as residents, workers and students, made sick by the toxic dust and debris that filled the air after the attacks, and by supporting the men and women in uniform who take risks and make extraordinary sacrifices to keep us safe. But it does not end there. That is 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. On this Sept. 11, as we reflect on this painful tragedy, let us also recommit ourselves to this historic task.