Russian natural gas is again being delivered by ship to an American port, according to news reports. Bloomberg says the tanker Catalunya Spirit, carrying fuel from thousands of miles away, was set to arrive in Puerto Rico last week. Such a transaction makes little sense, as the U.S. is the world’s largest gas producer.

What explains the mystery is the Merchant Marine Act of 1920, also known as the Jones Act. The law says that ships carrying cargo between U.S. points must be built, 75% owned, and 75% crewed by Americans. This inflates prices for compliant vessels and domestic shipping overall.

It’s a particular problem for liquid natural gas, since there are zero LNG tankers that meet Jones Act rules. That means Puerto Rico effectively is barred from importing gas from LNG terminals in Georgia or Louisiana. As a result, it apparently turned to Siberia. The same happened two winters ago in New England, where gas is short due to a lack of pipeline capacity. A tanker of Russian gas was unloaded in Boston. How is this an “America First” policy?

Earlier this year President Trump considered a Jones Act waiver to let foreign LNG tankers bring U.S. gas to the Northeast and Puerto Rico. But news reports suggested that Republicans in shipbuilding regions talked him out of it. “In a lot of states,” Louisiana Senator John Kennedy said, “it would mean his electoral prospects were as dead as fried chicken.”

Nonsense. The enormous gains from paring back the Jones Act would benefit all Americans. Consider an April study from the Organization for Economic Cooperation and Development. “The Act evidently creates large cost inefficiencies,” it says, “by protecting the shipbuilding industry—a tiny economic sector in the U.S.—at the expense of other U.S. industries with enormous economic potential.”