Washington is waking up to the perilous state of U.S. commercial shipping. Rep. Mike Gallagher (R., Wis.), chairman of the House Select Committee on the Chinese Communist Party, recently lamented the U.S. merchant fleet’s dwindling numbers and lack of mariners, while Sen. Mark Kelly (D., Ariz.) and Adm. Samuel Paparo, commander of the U.S. Pacific fleet, cited the fleet’s diminutive size as a national-security vulnerability. Mr. Kelly was one of 19 congressional signatories of a January letter to President Biden calling for improvements to the U.S. shipping and shipbuilding industries.

We’re heartened that policymakers are finally paying attention to the U.S. commercial fleet’s long-term decline and its dire national-security implications. But for the most part they’ve ignored the sector’s heaviest policy anchor—protectionism. Almost since America’s founding, the federal government has relied on subsidies and protectionist laws to develop the maritime industry. Numerous such measures remain in place, including both the 1920 Jones Act’s prohibition on using foreign-built vessels to transport goods within the U.S. and a 50% tariff on foreign repair and maintenance.

These and related policies have failed to create a vibrant maritime sector and have instead degraded it by handing U.S. shipping and shipbuilding industries a captive domestic market and discouraging scale, efficiency, innovation and specialization. After more than two centuries of protectionism, the U.S. maritime sector has gone from being one of the world’s most competitive to one of the least.

U.S.-built tankers cost about four times as much as those constructed abroad. The commercial fleet has lost hundreds of oceangoing vessels since the 1950s, and the few that remain are on average significantly older than their international counterparts.

While U.S. allies churn out scores of ships each year, you can count U.S. shipyards’ annual deliveries on one hand. Last year they collectively delivered one large oceangoing merchant ship, and the next won’t arrive until 2026. A recent Journal article described the country’s shipbuilding industry as being in “disarray.”

The government protections U.S. shipyards and the broader maritime sector enjoy have proved far more effective at funneling money to special interests than fostering a healthy industry. Adversaries would be hard-pressed to come up with a more effective formula for sabotaging the U.S. fleet.

Subsidies alone can’t fix these problems, and they’ve been tried. Massive “construction differential subsidies” in the 1970s and early 1980s yielded underwhelming results. Given the gaping price differences between U.S. and foreign-built ships today, more subsidies would cost taxpayers a fortune at a time of record budget deficits.

Instead of more industry coddling, systemic reform is needed, and this means tackling protectionism, injecting competition into the U.S. market, and engaging allies’ impressive shipbuilding capabilities. Congress should move away from a maritime policy rooted in 18th-century norms.

The starting point is reforming the Jones Act. To encourage the fleet’s growth and modernization, American firms need to be able to purchase new oceangoing ships from allied shipyards. Japan and South Korea are among the world’s foremost shipbuilders. Letting Americans use their advanced shipyards would generate an influx of new ships, boost U.S. mariner employment, motivate U.S. shipbuilders to innovate, and increase U.S. supply-chain efficiency.

Congress should also scrap the 50% tariff, which U.S. shippers pay because repairs at domestic shipyards are so expensive, or at least exempt allied shipyards. Both reforms are hardly radical, particularly given the U.S. Navy’s reliance on foreign-built sea-lift ships and recent attempts to expand its use of allied shipyards for maintenance needs.

For too long Washington has ignored the decline of the country’s maritime sector. Mounting international challenges have brought much-needed scrutiny and should prompt an overhaul of the country’s antiquated shipping policies. Any such effort must include the removal of protectionist measures that have long held the U.S. fleet back.