At the close, the Dow Jones industrial average had fallen 1.1 percent, while the broad S&P 500 index lost 0.4 percent and the tech-heavy Nasdaq composite index fell 0.2 percent.
During the afternoon, Iran attacked targets in the United Arab Emirates. Earlier, it was reported to have struck a US military ship.
Events caused oil prices to rise sharply; at 10 p.m., a barrel of North Sea oil cost approximately $114.
The logistics industry reacted with significant concern to the escalating situation. Transport giant FedEx fell just over 9 percent, while shipping company UPS fell more than 10 percent.
