The United States, Australia and the United Kingdom formed a pact in 2021 to boost the three nations’ collective deterrence in the Indo-Pacific. That AUKUS agreement is vital but there is more work to do: The U.S. should double its submarine production.

Under the first pillar of the AUKUS agreement, the U.S. would sell our attack submarines to Australia. In exchange, Australia would expand basing for U.S. submarines. In the second pillar, all three nations would share advanced technology.

Attack submarines are among our most effective weapons and the crown jewels of U.S. military power. Undersea warfare is one of the few areas in which we retain a competitive advantage over the Chinese military.

Aukus has bipartisan support because of its potential to improve the national security of all three nations. Implementing this deal will require a historic amount of cooperation and trust among the three countries and, here at home, between the executive and legislative branches.

As it stands, the AUKUS plan would transfer U.S. Virginia-class submarines to a partner nation even before we have met our own Navy’s requirements. The U.S. Navy’s military requirement is 66 nuclear attack submarines. Today, there are only 49 in the fleet. And the Navy projects its inventory will decline to 46 by 2030 as older nuclear submarines retire faster than they are replaced.

Worse still, demands on our submarine maintenance capabilities have also stretched our military’s readiness. Nearly 40% of U.S. attack submarines cannot be deployed because of maintenance delays. For example, the USS Connecticut had an accident in the South China Sea in 2021 and likely won’t be operational until 2026.

The U.S. submarine industrial base is producing an average of 1.2 Virginia-class attack submarines a year, short of the two our Navy needs. There are many reasons for this underperformance. For years, the U.S. government purchased only one submarine annually—hardly enough to maintain a strong industrial base.

By comparison, during the 1980s we bought four times as many. The effort to ramp up production to a rate of two attack submarines a year has been plagued with workforce and supply-chain challenges.

To keep the commitment made under AUKUS, and not reduce our own fleet, the U.S. would have to produce between 2.3 and 2.5 attack submarines a year.

Improvements in submarine maintenance and more forward basing of submarines will help increase deployment of the submarine fleet, making the deterrence effect of these weapons even stronger. Australian investment in U.S. shipyards will also help. But we can’t afford to shrink the overworked U.S. submarine fleet at a dangerous moment.

China’s President Xi Jinping has instructed the People’s Liberation Army to be ready for a Taiwan invasion by 2027. Time is of the essence.

Fortunately, there is a solution. President Biden should immediately send Congress a request for supplemental appropriations and authorities—including a detailed implementation plan—that increases U.S. submarine production to 2.5 Virginia-class attack submarines a year. It is time to make generational investments in U.S. submarine production capacity that include supplier and workforce development initiatives.

There is precedent for such a bold investment. Men, women and industries answered the call at the outset of World War II to produce weapons and materiel. During the Cold War, the U.S. rapidly built a nuclear Navy that was second to none. To fulfill the promise and benefit of the AUKUS agreement, we need such clarity of purpose once again.

Mr. Wicker, a Republican, is a U.S. senator from Mississippi and ranking member of the Senate Armed Services Committee.