The sanctions against 30 people, companies and ships come as President Donald Trump has massed the largest US buildup of warships and aircraft in the region in decades and has threatened to use military action in a bid to get Iran to constrain its nuclear program. The latest round of talks between US officials, including envoy Steve Witkoff, and Iranian negotiators via mediator Oman are scheduled for Thursday in Geneva. The new sanctions imposed by the Treasury Department's Office of Foreign Assets Control include a list of ships accused of being part of Iran's "shadow fleet," which refers to rusting oil tankers that smuggle oil for countries facing stiff sanctions.