Transcript for Biden addresses foreign powers: ‘America is back’
The president also spent time on the world stage today, more like a zoom meeting with world leaders. . His message, the U.S. Is back and so are its leaders. The U.S. Officially back in the peace accord. There was also the moment that looks like the rest of us in this pandemic when Boris Johnson had a tell Angela Merkel of Germany to mute her computer. Here's Jonathan Karl tonight. Reporter: Today in his first major speech on the world stage, president Biden declared an end to Donald Trump's America first, America alone foreign policy. I'm sending a clear message to the world, America is back. The transatlantic alliance is back, and we're not looking we are looking forward together. Reporter: President Biden has already taken several concrete steps to erase trump's foreign policy initiatives. He's rejoined the Paris climate accords and the world health organizations. He's said he wants to restart nuclear talks with Iran, and today Biden talked of working closely with allies trump delighted in publicly criticizing and pushing aside. Let me erase any lingering doubt. The united statewill work closely with our European union partners in the capitals across the continent. Reporter: Biden was addressing European allies remotely, a conference that had all the look of a large zoom call. Can everybody hear me? Wave if you can hear me. Reporter: It came with technical difficulties, too. In a moment we all can relate to, British prime minister Boris Johnson reminding the German chancellor to mute her line. Can you hear us Angela? That's okay, that's all right. I think you have to mute. Reporter: Later Johnson, who had been friendly with trump, enthusiastically welcomed Biden's abrupt change in course. America is unreservedly back as the leader of the free world, and that is a fantastic thing. That was really something. Jon Karl with us from Washington. That was quite a welcome from Boris Johnson. It got some attention because he was so close for so long to former president trump. Reporter: David, there was no European leader closer to trump than Johnson, not even close. Trump often boasted of their friendship. At one point he referred to Johnson as Britain trump, and there you had Boris Johnson enthusiastically greeting Biden's efforts to undo trump's policies. That was really something. One other thing underscored in Biden's speech, he criticized Vladimir Putin and called for a united front against Russia. Our chief Washington correspondent Jonathan Karl on a Friday night. Thank you.
This transcript has been automatically generated and may not be 100% accurate.