Policy experts say gas and oil prices could continue to rise if concerns over the Strait of Hormuz persist. The State Department is warning Americans traveling overseas to stay vigilant following the escalating conflict in the Middle East. Gas prices are now back up to an average of $4 a gallon nationwide. Then we will see the physical delivery shortfall that we saw before, with diesel prices, gas prices and airline fuel jumping up to near-record highs," said Jacquez. The State Department says U.S. citizens and nationals can sign up for its Smart Traveler Enrollment Program to receive the latest security and safety alerts for their destination.