The law helps stabilize the nation’s maritime industry. It facilitates some 650,000 jobs across our vast system of shipyards, ports and waterways and adds $150 billion annually to our economy. Ending the policy would hit the wallets of skilled American workers.

Opponents of the law value our economy and security, but their proposals risk both. We should dispense with the idea that repealing the Jones Act would save Americans money. Even if we allowed foreign vessels into our domestic sea trade, they would still sail under our wage, immigration and trade fees. These costs would get passed on to consumers.

Critics rightly recognize our diminished shipbuilding capacity, but that isn’t the fault of the Jones Act. Nor would repealing it reignite freedom’s forge. It would weaken our maritime workforce when we need it most.

Naval strategists have noted that American sea power creates a self-reinforcing system: Growth in commercial shipbuilding facilitates growth in the battle fleet, and vice versa.

This is not a time to stress-test this historical truth. China put 30 warships to sea last year, and it boasts the world’s most merchant vessels. Meanwhile, the U.S. naval fleet shrank, and we now rank 70th in commercial shipping inventory. Repealing the Jones Act would narrow the already shrinking margin of American naval superiority.

Sen. Roger Wicker (R., Miss.)

Tupelo, Miss.

Mr. Wicker is ranking member of the Senate Armed Services Committee.

This letter originally appeared in the Wall Street Journal. Read it here.