The U.S. Navy plans to upgrade a whole lot of Tomahawk land-attack cruise missiles. Potentially more than a thousand of them.

The rest, the service wants to dismantle. The result would be a much more capable, but potentially much smaller, U.S. cruise-missile arsenal.

Capt. John Red, the Navy’s Tomahawk program manager, detailed the plan at the 2020 Surface Navy Association Symposium in Virginia in mid-January 2020. “Modernization ensures Tomahawk’s relevance now and in the future,” according to a slide Red presented at the symposium.

No fewer than 89 Navy destroyers and cruisers plus 54 attack submarines and four guided-missile submarines are compatible with the 20-feet-long Tomahawk, the first model of which entered service in 1983.

Tomahawks can launch from the Mark 41 vertical-launch systems aboard surface ships or from a submarine’s own vertical launchers or torpedo tubes. All told, the Navy deploys around 10,000 Tomahawk launchers, although only a fraction of that total at any given time actually carries cruise missiles.

Raytheon builds Tomahawks at a facility in Arizona. Each missile costs the Navy more than $1 million. In 2020 the Navy has around 4,000 Tomahawks. But that number is set to fall as the fleet upgrades some missiles and disposes of others.

The plan, Red explained, was to upgrade all Block IV Tomahawks to a new Block V standard with improved guidance and extended range. Using a combination of GPS, inertial and terrain-matching guidance systems, a Tomahawk can strike targets as far as 1,000 miles away.

The Block IVs entered service in 2004, complementing older Block IIIs that joined the fleet in the mid-1990s. The Block IVs, which boast a two-way datalink for mid-flight changes to their courses and targets, are supposed to have 30-year service lives.

But to remain effective for the last 15 years, they need upgrades, Red said. “The future is now,” one of his slides read.

The Navy plans to cycle all of its Block IV cruise missiles through a mid-life “recertification,” during which Raytheon will add a new guidance system. The result is a Block V missile. The fleet is in the process of demilitarizing the remaining Block IIIs.

The first five Tomahawk Block Vs officially are test missiles. But they will sail with front-line warships. The Navy could fire them in combat as a sort of operational test “to demonstrate their capabilities,” Red said.

There will be three Block V variants. The baseline missile just has the new guidance system. The Block Va adds additional seeker modes for hitting surface ships. The Block Vb adds a new warhead with different modes for destroying buried targets.

The Navy asked Congress for $300 million to support the recertification effort in 2020.

Red said the Navy wants to modernize 90 missiles per annual budget cycle. Realistically, that means the fleet could get around 1,400 Block Vs through the mid-2030s. Unless Congress pays for more missiles, the Tomahawk arsenal could shrink by half or more over that timespan.

And that’s not taking into account any Tomahawks the Navy fires in combat. In just the last couple of years, the fleet has fired more than 100 Tomahawks at targets in Syria.

“If the U.S. continues to utilize Tomahawks at historically average levels ― the U.S. Navy might need thousands of missiles over the next decade or more,” Jonathan Bergner wrote at Defense News.

Without continuing support from Congress for Tomahawk-production, “we may one day find ourselves in a situation where we have the will to strike an adversary but lack the best means to do so,” Bergner added.

The Tomahawk isn’t the Navy’s only missile, of course. Other types in coming years could fill the gap that results from a shortfall in Tomahawk modernization.

The Navy is developing a new long-range anti-ship missile based on Lockheed Martin’s air-launched stealthy cruise missile. And a new hypersonic land-attack missile could enter service in the mid-2020s.

David Axe serves as Defense Editor of the National Interest. He is the author of the graphic novels  War Fix, War Is Boring and Machete Squad.