On Tuesday afternoon, at about 4 p.m. Eastern, the American public first learned that Iran was holding 10 American sailors and two small, riverine boats. In the immediate hours after the incident, the pundit classes inside the beltway (author included) exploded Twitter into a hyperbolic mess, as it tends to do, while Tehran, eight and a half hours ahead, mostly slept.

By morning, the sailors were released. This is not a story about that incident, though it does provide some context. This is a story about those boats.

The sailors were on a couple of Riverine Command Boats, first introduced into the United States Navy in 2007. Unlike the Navy's ocean-going "blue-water" vessels, these are much smaller boats built for "brown water," or rivers and waters close to coast. For reference, they're similar in concept to the Swift Boats used by the United States in Vietnam and popularized in the film Apocalypse Now. While Iraq is no Vietnam in terms of water, it still has over 3000 miles of sometimes-navigable rivers.