WATCH: NBC News' Andrea Mitchell reports from Helsinki. She talks with Lester Holt about what to expect during the Trump-Putin summit. | NBC Nightly News with Tom Llamas

The iconic Andrea Mitchell signs off from Andrea Mitchell Reports after 17 years in the anchor chair. She will continue with NBC News, as chief Washington correspondent and chief foreign affairs correspondent. | MS NOW

The White House said Monday it was reviewing how Jeffrey Goldberg, the editor-in-chief of The Atlantic magazine, was accidentally added to an encrypted group text with people who appeared to be members of President Donald Trump’s administration. In the chat, they discussed plans to launch airstrikes against Houthi militants in Yemen. NBC News' Andrea Mitchell reports on the situation and interviews Goldberg about the remarkable lapse. | NBC Nightly News with Tom Llamas