Transcript for Biden unveils national security team
And this evening now marks three weeks since the election and tonight, the transition is now officially under way. President-Elect Joe Biden acting quickly, introducing today the first six members of his national security and foreign policy team, making historic and you will hea from them. The change in tone already and what each of them signaled. President trump announcing today with little notice that he would hold a briefing at the white house, and it was brief, about 64 seconds long. He took no questions, celebrating the stock market. We have both parts covered. Rachel Scott at Biden transition headquarters in Delaware. Reporter: With the transition finally underway, president elect Joe Biden today unveiling much of his national security team with a clear message -- the era of America first is over and we're ready to work with our allies again. It's a team that reflects the fact that America is back, ready to lead the world, not retreat from it. Reporter: President trump's name mentioned not even once, but everything about today's event amounted to a sharp rebuke. On stage, everyone socially distanced and in masks. The podium wiped down after each speaker. Most of Biden's nominees, Washington veterans he's worked with for years. Longtime aide Tony blinken, now up for secretary of state. As the President-Elect said, we can't solve all the world's problems alone. We need to be working with other countries. We need their cooperation. We need their partnership. Reporter: Biden's nominee for ambassador to the united nations, Linda Thomas eenfield, a 35-year veteran of the state department. I want to say to you, America is back. Multilateralism is back. Diplomacy is back. Reporter: Homeland security nominee Alejandro mayorkas, the first Latino nominated for the post and the son of immmigrants, setting a new tone. The department of homeland security has a noble mission to help keep us safe and to advance our proud history as a country of welcome. Reporter: And Avril Haines, the first woman nominated as director of national intelligence, a role that became politicized under trump. Mr. President-Elect, you know that I have never shied away from speaking truth to power. Reporter: The president elect also tapping his longtime friend John Kerry for a new position, climate czar, with a permanent seat on the national security council. President Joe Biden will trust in god and he will also trust in science to guide our work on Earth to protect god's creation. Reporter: With the transition now underway, Biden will soon receive national security briefings. They've been very forthcoming, offering all access and so we're going to be starting those on a regular basis. Reporter: But no contact yet with from president trump. Mr. President-Elect, will you meet with president trump? Of course I would, if he asked. Let's get to Rachel Scott with us live tonight. And Rachel, the election, as I mentioned, three weeks ago tonight. Feels like G time ago. The transition only beginning last night, officially, but tonight, you're learning the Biden team already speaking with all federal agencies and they've been in touch with Dr. Fauci, as well? Reporter: Yeah, that's right, David. President-Elect Joe Biden saying as soon as those federal agencies were given the green light, the outreach was immediate and sincere. His team now in touch with Dr. Anthony Fauci and operation warp speed about plans to distribute a coronavirus vaccine and this does open the door for Joe Biden to start getting those critical and classified national security brie David? Rachel Scott live in Wilmington for us. As I mentioned, the president suddenly holding a brief today at the white house. It lasted just 64 seconds and came amid a rise on Wall Street. The Dow soaring today, Toppi 30,000 for the first time in history. The president came before the cameras to celebrate the Dow after repeatedly saying the market would crash if Joe Biden was elected. Wall Street analysts tonight saying the transition now under way helped fuel it. Here's what the president said. The stock market's just broken 30,000, never been broken, that number, that's a sacred number, 30,000, nobody thought they'drr see it. And I just want to congratulate all the people within the administration that worked so hard and most importantly, I want to congratulate the people of our country. The president left without taking anyquestions, but Jon Karl takes the questions, he's right here tonight, live in Washington again. I know you were in the briefing room. We know the transfer of power now officially under way. President trump, though, still hasn't conceded, so, what's the thinking right now inside the white house, what are you learning? Reporter: Well, David, I'm told the president is spending a lot of time in the private dining room right next to the oval office. He's talking to friends an supporters at all hours of day and into the evening. I'm told he is coming around to the reality that Joe Biden will be the next president. But as one of those who has spoken to the president regularly over these past three weeks put it to me, quote, this is a man who can't say he is sorry and who can't say he lost, he needs the world to believe it was stolen from him. So I'm told to expect the lawsuits will continue right until the bilgtter end and the president is telling his friends and supporters that he is not going to leave the world of politics no matter what happened. In fact, one person who I spoke to today said that the president told him flatly he intends to run for president again. David? Jon Karl with us tonight. Jon, thank you.
This transcript has been automatically generated and may not be 100% accurate.