WASHINGTON — The United Kingdom’s plan to increase its nuclear warhead stockpile will not be impacted should the U.S. scrap a new submarine-launched nuclear warhead, a British Ministry of Defence official said Tuesday.

“The number of warheads we need for the future is not determined by anything which the U.S. is doing on W93,” Angus Lapsley, the MoD’s director general for strategy and international issues, said during an event hosted by the Center for Strategic and International Studies.

“The U.S. has a warhead program, and we have a warhead program,” Lapsley added. “Because we share the same missile, and therefore use the same aeroshell that wraps around the warhead, there is a certain amount of, sort of, mutual support we can provide each other in taking those programs forward. But you [still] end up with a U.K. warhead and an American warhead.”

The W93 is a new nuclear warhead design for use aboard submarine-launched ballistic missiles. The program was unveiled as part of the Trump administration’s fiscal 2021 budget request and is in the earliest stages of design work at both the Pentagon and the National Nuclear Security Administration, which manages warhead production.

The creation of a new warhead design — the first in decades after a series of life-extension and modernization efforts on existing warheads — quickly drew political fire from nonproliferation advocates. It is also seen as particularly vulnerable on the political stage as the debate around the FY22 budget begins. While it is unknown if U.S. President Joe Biden’s budget request includes funding for the W93, it is expected some Democrats will push to cancel the program and invest funding elsewhere.

At the same time the plans for the W93 were announced, the United Kingdom revealed that it is working on a new warhead design for its Trident missile-armed nuclear submarine fleet. The U.S. and U.K. plan to collaborate around the W93 to find commonalities in the designs.

The issue took on extra focus after the reveal last month that the U.K. plans to expand its stockpile of nuclear warheads. London plans to have “no more” than 260 warheads, which reverses a decision made a decade ago to cut the maximum number from 225 to 180 by the mid-2020s; the decision could result in increasing the stockpile by more than 40 percent overall.

Lapsley shot down the idea that the increase in warheads was related to the agreement between the U.S. and U.K. to jointly develop new submarine-launched warheads.

The concept that the U.K. somehow received a buy-one-get-one-free deal from the U.S. on the W93, and that explains why warhead numbers are going up, is not true, he said.

“It is important to us that the W93 program that the U.S. Navy is pursuing moves ahead. But we have our own program and, you know, we will take our own program forward” regardless of what happens, he added.

Aaron Mehta was deputy editor and senior Pentagon correspondent for Defense News, covering policy, strategy and acquisition at the highest levels of the Defense Department and its international partners.

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