Watch speech here. Start video at 31:00.

Read transcripts of all Biden's new cabinet picks here.

Mr. President elect, Madam Vice President elect, thank you. Mr. President elect, I am honored and humbled by the immense responsibility that you’ve placed in me of being your National Security Advisor. I pledge to you and to the American people that I will work relentlessly in service of the mission you have given us to keep our country and our people safe, to advance our national interests, and to defend our values. I pledge to the exceptional national security team you see behind me and to the brilliant and diverse career professionals across our government, that I will manage a humane and rigorous decision making process that honors their work. And I pledge to my parents who taught my brothers, my sister and me to work hard, tell the truth, and serve others, that I will do my utmost to make you proud. Sir, we will be vigilant in the face of enduring threats from nuclear weapons to terrorism, but you have also tasked us with re-imagining our national security for the unprecedented combination of crises we face at home and abroad.

The pandemic, the economic crisis, the climate crisis, technological disruption, threats to democracy, racial injustice, and inequality in all forms. The work of the team behind me today will contribute to progress across all of these fronts. You have also tasked us with putting people at the center of our foreign policy. You’ve told us that the alliances we rebuild, the institutions we lead, the agreements we sign, all of them should be judged by a basic question. Will this make life better, easier, safer for families across this country? Our foreign policy has to deliver for these families. And perhaps most importantly, you’ve tasked us with helping unite America, as you said in your remarks through our work to pull people together to tackle big challenges. My wife Maggie, the love of my life and my partner in all things, served as a Senior Advisor to Senator John McCain. She and I shared this commitment to common ground deep in our bones.

To the American people, I have the honor of serving as Joe Biden’s security advisor when he was Vice President. I’ve learned a lot about a lot. About diplomacy, about strategy, about policy, but most importantly, about human nature. I watched him pair strength and resolve with humanity and empathy. That is the person America elected, and that is also America at its best. So Mr. President elect, thank you for giving this kid from the heartland and extraordinary opportunity to serve the country I love.