The White House says Trump will speak to the country on Monday at 8 p.m. CDT from Fort Myer in Arlington, Virginia.
Trump and his national security team met Friday at the Camp David presidential retreat in Maryland to reach agreement on a strategy.
Trump tweeted over the weekend that he had made a decision. Defense Secretary Jim Mattis, traveling in Afghanstan on Sunday, also said Trump had reached a decision. Mattis declined to discuss specifics before Trump's announcement.
It will be Trump's first formal address to the nation as president, and it follows a period of isolation for Trump following his comments about racial violence in Charlottesville, Virginia.