A House subcommittee has advanced its portion of the annual defense policy bill that would block the Pentagon from deploying low-yield nuclear warheads, following a partisan debate.

The strategic forces subcommittee voted Wednesday in an 10-8 party-line vote to approve its section of the National Defense Authorization Act (NDAA), including four provisions that Republican members objected to.

A Republican amendment to nix the provisions, offered by Rep. Liz Cheney Elizabeth (Liz) Lynn CheneyOVERNIGHT ENERGY: Cheney asks DOJ to probe environmental groups | Kudlow: 'No sector worse hurt than energy' during pandemic | Trump pledges 'no politics' in Pebble Mine review Cheney asks DOJ to probe environmental groups Press: The big no-show at the RNC MORE (R-Wyo.), failed 8-10.

The fight in the subcommittee could signal a more contentious and lengthy debate when the full committee takes up the bill next week.

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On Wednesday, Republicans argued Democrats were departing from longstanding practice to keep the subcommittee's portion of the bill strictly bipartisan and wait until full committee to address controversial issues.

Rep. Mike Turner Michael Ray TurnerHispanic Caucus campaign arm endorses slate of non-Hispanic candidates Overnight Defense: Trump announces 'snapback' of sanctions on Iran | Uniformed personnel at Dem convention under investigation | Netanyahu calls reported F-35 deal 'fake news' Democrats go big on diversity with new House recruits MORE (R-Ohio), the subpanel’s top Republican, said his fellow GOP members were "deeply disappointed" in the markup, saying it makes Americans "less safe."

“This is not an issue of our having differing legislative priorities," he said. "This is that many of the provisions that are in this mark we don’t believe are appropriate for legislation."

The subcommittee’s portion of the NDAA also includes a provision that would prevent the Trump administration from withdrawing from the Open Skies Treaty. The multilateral accord allows signatories to conduct unarmed observation flights over the entirety of other countries in hopes of increasing transparency and reducing the risk of miscalculation.

Republicans have targeted the treaty over alleged Russian violations, claiming that Moscow is denying U.S. requests to fly over some parts of the country. NDAAs passed under a GOP-controlled Congress have restricted treaty-related funding.

Republicans further objected to provisions in the bill on plutonium pit production capacity and notifications of meetings held by the Nuclear Weapons Council.

Chairman Jim Cooper Jim CooperHouse Democrat to DeJoy: 'Is your backup plan to be pardoned like Roger Stone?' House Democrats call on State Department for information on Uighur prisoner Ekpar Asat Pelosi weighing bringing House back from August recess early over USPS issues: reports MORE (D-Tenn.) defended his decision to include the provisions, saying the panel has the best expertise to tackle nuclear debates.

“This year I am trying to debate more issues at the subcommittee level so that members with the most expertise can, I hope, resolve these issues during the afternoon instead of late at night during the [Armed Services] markup next week,” he said.

The Trump administration proposed the submarine-launched low-yield warhead, known as the W76-2, as part of its Nuclear Posture Review. The administration argues it is needed to deter Russia, but opponents argue it is destabilizing and could lower the threshold for the country's willingness to use nuclear weapons.

The National Nuclear Security Administration is expected to finish production of the warheads this year, but the Pentagon still needs money to deploy them.

The NDAA would block funding for the Pentagon to deploy the warheads. Full committee Chairman Adam Smith David (Adam) Adam SmithWhen 'Buy American' and common sense collide Overnight Defense: Marine Corps brushes off criticism of Marines' appearance in GOP convention video | US troops injured in collision with Russian vehicle in Syria | Dems ask for probe of Vindman retaliation allegations Democrats press Pentagon watchdog to probe allegations of retaliation against Vindman brothers MORE (D-Wash.) has said he want to “kill” the low-yield warhead.

“Regarding low-yield, the last sixty years of nuclear deterrence strategy was based, in part, on the U.S. strategic nuclear submarine force, the most survivable leg of the triad, never being used as a tactical nuclear platform,” Cooper said. “I hope that members realize that adding a small number low-yield weapons to our submarines will actually decrease, not increase, our strategic power by subtracting priceless missile tubes and by risking exposure of our submarines to attack.”

Cooper added that he is not opposed to low-yield weapons in general, highlighting that air assets already have them.