When will there next be a lethal confrontation between the national military forces of Iran and the United States either in Iran or at sea?

Amid a deal to relocate American prisoners in Iran, the US is warning vessels to stay away from Iranian waters to avoid seizure by Iranian forces as tensions regarding the country's nuclear program continue (AP, NBC News, US Naval Institute, Times of Israel). A lethal confrontation is one that results in at least one fatality (total, not each) for the national military forces of either side. For the purposes of this question, Iran's national military forces include the Revolutionary Guard Corps and Law Enforcement Forces. A lethal confrontation taking place in Iranian airspace or international airspace over the sea would count, and a fatality must occur during the question's open period to count. Confused? Check our FAQ or ask us for help. To learn more about Good Judgment and Superforecasting, click here. To learn more about how you can become a Superforecaster, see here. For other posts from our Insights blog, click here.