The United States has been building up a military presence around Iran for weeks, even as negotiators from both countries plan to meet later this week in hopes of finding a diplomatic solution to the escalating tensions. David E. Sanger, a national security correspondent for The New York Times, explains what President Trump hopes to achieve through potential military action, and why he has chosen this moment. Guest: David E. Sanger, the White House and National Security Correspondent for The New York Times. Background reading:  Mr. Trump has said he is considering a targeted strike against Iran that could be followed by a larger attack. As Mr. Trump weighs military action, he has declined to make a clear case for why, or why now. Photo: Pool photo by Fazry Ismail For more information on today’s episode, visit nytimes.com/thedaily. Transcripts of each episode will be made available by the next workday.  Subscribe today at nytimes.com/podcasts or on Apple Podcasts and Spotify. You can also subscribe via your favorite podcast app here https://www.nytimes.com/activate-access/audio?source=podcatcher. For more podcasts and narrated articles, download The New York Times app at nytimes.com/app. Hosted by Simplecast, an AdsWizz company. See pcm.adswizz.com for information about our collection and use of personal data for advertising.