Democrats in the House and Senate on Tuesday unveiled legislative language that would ban research, development, manufacturing, and fielding of the planned low-yield, submarine-launched ballistic-missile warhead for which Congress approved $65 million in funding during the fiscal year that begins in 13 days.

Rep. Ted Lieu (D-Calif.) sponsored the House bill, with co-sponsors Reps. John Garamendi (D-Calif.), Earl Blumenauer (D-Ore.), and Adam Smith (D-Wash.). Sen. Ed Markey (D-Mass.) sponsored the Senate bill, according to a Tuesday press release.

The legislation would specifically prohibit spending funds appropriated to the departments of Energy and Defense in fiscal 2019 for work on the warhead.

In its Nuclear Posture Review issued in February, the Trump administration said the United States needs the low-yield warhead to check similarly powerful Russian weapons, which some in the administration fear Moscow might use to win a war it starts, but cannot finish, with conventional weapons.

Opponents of the warhead, including many congressional Democrats, say the existing U.S. arsenal is sufficient to deter the Kremlin from using a low-yield nuclear weapon on any battlefield. They say any use of any nuclear weapon could spiral into a full-scale, civilization-ending nuclear war.

“We already have a nuclear deterrent that is more than adequate to achieve our national security goals. Funding new, low-yield weapons would only draw us further into an unnecessary nuclear arms race and increase the risks of miscalculation,” Smith, ranking member of the House Armed Services Committee and an outspoken opponent of the planned warhead, said in a prepared statement Tuesday.

Nevertheless, a multiagency appropriations package passed by Congress last week provides $65 million for the National Nuclear Security Administration (NNSA) to create the weapon by dialing back the yield of an unspecified number of existing W76 warheads. The warheads tip Trident II-D5 missiles carried aboard Ohio-class submarines.

In an appropriations subcommittee hearing in April, Sen. Dianne Feinstein (D-Calif.) said the NNSA expects the low-yield W76 will cost a total of $125 million or so to build over the course of the government’s 2019 and 2020 fiscal years.