US Deploys New Low-Yield Nuclear Submarine Warhead


Date:2020-04-19 Source:FAS By:Globalmil Viewed:

Posted on Jan.29, 2020 in Nuclear Weapons, Russia, United States by Hans M. Kristensen
By William M. Arkin* and Hans M. Kristensen
作者:汉斯·克里斯滕森(Hans M. Kristensen)
威廉·阿金(William M.Arkin)*和汉斯·克里斯滕森(Hans M.Kristensen)

The USS Tennessee (SSBN-734) at sea. The Tennessee is believed to have deployed on an operational patrol in late 2019, the first SSBN to deploy with new low-yield W76-2 warhead. (Picture: U.S. Navy)
The US Navy has now deployed the new W76-2 low-yield Trident submarine warhead. The first ballistic missile submarine scheduled to deploy with the new warhead was the USS Tennessee (SSBN-734), which deployed from Kings Bay Submarine Base in Georgia during the final weeks of 2019 for a deterrent patrol in the Atlantic Ocean.

The W76-2 warhead was first announced in the Trump administration’s Nuclear Posture Review (NPR) unveiled in February 2018. There, it was described as a capability to “help counter any mistaken perception of an exploitable ‘gap’ in U.S. regional deterrence capabilities,” a reference to Russia. The justification voiced by the administration was that the United States did not have a “prompt” and useable nuclear capability that could counter – and thus deter – Russian use of its own tactical nuclear capabilities.
We estimate that one or two of the 20 missiles on the USS Tennessee and subsequent subs will be armed with the W76-2, either singly or carrying multiple warheads. Each W76-2 is estimated to have an explosive yield of about five kilotons. The remaining 18 missiles on each submarine like the Tennessee carry either the 90-kiloton W76-1 or the 455-kiloton W88. Each missile can carry up to eight warheads under current loading configurations.
我们估计,田纳西号和后续潜艇上的20枚导弹中的一枚或两枚将单独或携带多颗装备W76-2的弹头。估计每颗W76-2的爆炸当量约为5吨。像田纳西号一样,每艘潜艇上剩余的18枚导弹携带90-吨W76-1或455-吨W88。 在当前的载荷配置下,每枚导弹最多可携带八颗弹头。
The first W76-2 (known as First Production Unit, or FPU) was completed at Pantex in February 2019. At the time, NNSA said it was “on track to complete the W76-2 Initial Operational Capability warhead quantity and deliver the units to the U.S Navy by the end of Fiscal Year 2019” (30 September 2019). We estimate approximately 50 W76-2 warheads were produced, a low-cost add-on to improved W76 Mod 1 strategic Trident warheads which had just finished their own production run.
首批W76-2(称为第一批生产单位,即FPU)已于2019年2月在潘太克斯(Pantex)制造完成。当时,NNSA表示“正按计划完成W76-2初始作战能力弹头的数量,并在2019财年年底之前(2019年9月30日)将其交付给美国海军”。我们估计大约生产了50颗W76-2弹头,这是对刚刚完成生产的改进型W76 Mod 1战略三叉戟弹头的低成本附加。
The W76-2 Mission

The NPR explicitly justified the W76-2 as a response to Russia allegedly lowering the threshold for first-use of its own tactical nuclear weapons in a limited regional conflict. Nuclear advocates argue that the Kremlin has developed an “escalate-to-deescalate” or “escalate-to-win” nuclear strategy, where it plans to use nuclear weapons if Russia failed in any conventional aggression against NATO. The existence of an actual “escalate-to-deescalate” doctrine is hotly debated, though there is evidence that Russia has war gamed early nuclear use in a European conflict.
Based upon the supposed “escalate-to-deescalate” doctrine, the February 2018 NPR claims that the W76-2 is needed to “help counter any mistaken perception of an exploitable ‘gap’ in U.S. regional deterrence capabilities.” The National Nuclear Security Administration (NNSA) has further explained that the “W76-2 will allow for tailored deterrence in the face of evolving threats” and gives the US “an assured ability to respond in kind to a low-yield nuclear attack.”
Consultants who were involved in producing the NPR have suggested that “[Russian President] Putin may well believe that the United States would not respond with strategic warheads that could cause significant collateral damage” and “that Moscow could conceivably engage in limited nuclear first-use without undue risk…”
参与制作《不扩散核武器条约》的顾问建议:“ [[俄罗斯总统]普京很可能相信美国不会以可能造成重大附带损害的战略弹头作出回应”,“莫斯科可以在没有不适当风险的情况下进行有限的核首次使用……”
There is no firm evidence that a Russian nuclear decision regarding the risk involved in nuclear escalation is dependent on the yield of a US nuclear weapon. Moreover, the United States already has a large number of weapons in its nuclear arsenal that have low-yield options – about 1,000 by our estimate. This includes nuclear cruise missiles for B-52 bombers and B61 gravity bombs for B-2 bombers and tactical fighter jets.
Yes, but – so the W76-2 advocates argue – these low-yield warheads are delivered by aircraft that may not be able to penetrate Russia’s new advanced air-defenses. But the W76-2 on a Trident ballistic missile can. Nuclear advocates also argue the United States would be constrained from employing fighter aircraft-based B61 nuclear bombs or “self-deterred” from employing more powerful strategic nuclear weapons. In addition to penetration of Russian air defenses, there is also the question of NATO alliance consultation and approval of an American nuclear strike. Only a low-yield and quick reaction ballistic-missile can restore deterrence, they say. Or so the argument goes.
All of this sounds like good old-fashioned Cold War warfighting. In the past, every tactical nuclear weapon has been justified with this line of argument, that smaller yields and “prompt” use – once achieved through forward European basing of thousands of warheads – was needed to deter. Now the low-yield W76-2 warhead gives the United States a weapon its advocates say is more useable, and thus more effective as a deterrent, really no change from previous articulations of nuclear strategy.
The authors of the NPR also saw the dilemma of suggesting a more usable weapon. They thus explained that the W76-2 was “not intended to enable, nor does it enable, ‘nuclear war-fighting.’ Nor will it lower the nuclear threshold.” In other words, while Russian low-yield nuclear weapons lower the threshold making nuclear use more likely, U.S. low-yield weapons instead “raise the nuclear threshold” and make nuclear use less likely. Undersecretary of Defense for Policy John Rood even told reporters that the W76-2 would be “very stabilizing” and in no way supports U.S. early use of nuclear weapons, even though the Nuclear Posture Review explicitly stated the warhead was needed for “prompt response” strike options against Russian early use of nuclear weapons.
《核态势评估》的编写者还看到了建议使用更多武器的两难境地。他们因此解释说,W76-2“无意于启用核武器,也不会启用核武器。” 换句话说,尽管俄罗斯的低当量核武器降低了核门槛,使核能使用的可能性更大,但美国的低当量武器却“提高了核门槛”,并降低了核使用的可能性。国防政策部副部长约翰·罗德(John Rood)甚至对记者说,W76-2将会“非常稳定”,并且绝不支持美国早日使用核武器,即使《核态势评估》明确指出弹头是针对俄罗斯早日使用核武器的“快速反应”打击选择所必需的。
“Prompt response” means that strategic Trident submarines in a W76-2 scenario would be used as tactical nuclear weapons, potentially in a first use scenario or immediately after Russia escalated, thus forming the United States’ own “escalate-to-deescalate” capability. The United States has refused to rule out first use of nuclear weapons.

The USS Tennessee (SSBN-734) in drydock at Kings Bay submarine base in September 2019 shortly before it returned to active duty and loaded with Trident D5 missiles carrying the new low-yield W76-2 warhead. (Photo: U.S. Navy)
田纳西号(SSBN-734)于2019年9月在金斯湾潜艇基地的干船坞内重返现役,并装载了搭载新低当量W76-2弹头的“三叉戟”(Trident) D5型导弹。(照片:美国海军)
Since the United States ceased allocating some of its missile submarines to NATO command in the late-1980s, U.S. planners have been reluctant to allocate strategic ballistic missiles to limited theater tasks. Instead, NATO’s possession of dual-capable aircraft and increasingly U.S. long-range bombers on Bomber Assurance and Deterrence Operations (BAAD) – now Bomber Task Force operations – have been seen as the most appropriate way to slow down regional escalation scenarios. The prompt W76-2 mission changes this strategy.
In the case of the W76-2, carried onboard a submarine otherwise part of the strategic nuclear force, amidst a war Russia would have to determine that a tactical launch of one or a few low-yield Tridents was not, in fact, the opening phase of a much larger escalation to strategic nuclear war. Thus, it seems inconceivable that any President would approve employment of the W76-2 against Russia; deployment on the Trident submarine might actually self-deter.
Though almost all of the discussion about the new W76-2 has focused on Russia scenarios, it is much more likely that the new low-yield weapon is intended to facilitate first-use of nuclear weapons against North Korea or Iran. The National Security Strategy and the NPR both describe a role for nuclear weapons against “non-nuclear strategic attacks, and large-scale conventional aggression.” And the NPR explicitly says the W76-2 is intended to “expand the range of credible U.S. options for responding to nuclear or non-nuclear strategic attack.” Indeed, nuclear planning against Iran is reportedly accelerating, B-2 bomber attacks are currently the force allocated but the new W76-2 is likely to be incorporated into U.S. Central Command (CENTCOM) war planning.
尽管关于新型W76-2的几乎所有讨论都集中在俄罗斯的情况上,但这种新型的低当量武器更有可能旨在促进对朝鲜或伊朗的首次使用核武器。《国家安全战略》和《不扩散核武器条约》都描述了核武器在对抗“非核战略攻击和大规模常规侵略”中的作用。《核态势评估》明确表明,W76-2的目的是“扩大应对核或非核战略攻击可靠的美国选择范围。” 实际上,据报导,针对伊朗的核计划正在加速,目前已分配了B-2轰炸机的攻击力量,但新的W76-2可能会纳入美国中央司令部(CENTCOM)的战争计划中。

Cheap, Quick, Simple, But Poorly Understood

In justifying the W76-2 since the February 2018 NPR, DOD has emphasized that production and deployment could be done fast, was simple to do, and wouldn’t cost very much. But the warhead emerged well before the Trump administration. The Project Atom report published by the Center for Strategic and International Studies in 2015 included recommendations for a broad range of low-yield weapons, including on long-range ballistic missiles. And shortly after the election of President Trump, the Defense Science Board’s defense priority recommendations for the new administration included “lower yield, primary-only options.” (This refers to the fact that the W76-2 is essentially little different than the strategic W76-1, “turning off” the thermonuclear secondary and thus facilitating rapid production.)
Initially, the military interest in a new weapon seemed limited. When then STRATCOM commander General John E. Hyten (now Vice Chairman of the Joint Chiefs of Staff) was asked during Congressional hearings in March 2017 about the military need for lower-yield nuclear weapons, he didn’t answer with a yes or no but explained the U.S. arsenal already had a wide range of yields:
最初,人们对新武器的军事兴趣似乎很有限。然后,在2017年3月的国会听证会上,美国战略司令部(STRATCOM)司令约翰•海顿(John E.Hyten)将军(现任参谋长联席会议副主席)被问及军队对低当量核武器的需求时,他没有回答是或否。解释说,美国军火库已经拥有广泛的当量:
    Rep. Garamendi: The Defense Science Board, in their seven defense priorities for the new administration, recommended expanding our nuclear options, including deploying low yield weapons on strategic delivery systems. Is there a military requirement for these new weapons?
    Gen. Hyten: So Congressman, that’s a great conversation to tomorrow when I can tell you the details [in closed classified session], but from a — from a big picture perspective in — in a public hearing, I can tell you that our force structure now actually has a number of capabilities that provide the president of the United States a variety of options to respond to any numbers of threats.

Later that month, in an interview at the Military Reporters and Editors Conference, Hyten elaborated further that the United States already had very flexible military capabilities to respond to Russian use of tactical nuclear weapons:
    John Donnelly (Congressional Quarterly Roll Call): The Defense Science Board, among others, has advocated development of new options for maneuvering lower yield nuclear warheads instead of just air delivered, talking basically about ICBM, SLBM. The thinking, I think, is that given the Russian escalate to win, if you like, or escalate to deescalate doctrine, the United States needs to have more options. What do you think about, that is my question. Especially in light of the fact that there are those who are concerned that this further institutionalizes the idea that you can fight and maybe even win a limited nuclear war.
    约翰·唐纳利(John Donnelly)(美国国会季刊编委):国防科学委员会等倡导开发新的方案,以操作低当量的核弹头,而不仅仅是空运,基本上是在谈论洲际弹道导弹,潜射弹道导弹(SLBM)。我的想法是,鉴于俄罗斯升级去赢得胜利,如果你愿意的话,可以升级到逐步降级理论,美国需要更多选择。您怎么看,这是我的问题。特别是考虑到有些人担心这进一步使您可以作战甚至可能打一场有限的核战争的想法制度化。
    Gen. Hyten: …we’re going to look at that in the Nuclear Posture Review over the next six months. I think it’s a valid question to ask, but I’ll just tell you what I’ve said in public up until this point, and as we go into the Nuclear Posture Review.
    海顿将军:…我们将在接下来的六个月的《核态势评估》中对此进行研究。 我认为这是一个合理的问题,但是在此之前,我将告诉大家我在公开场合所说的话,以及我们进入《核态势评估》的时间。
    …in the past and where I am right now is that I’ll just say that the plans that we have right now, one of the things that surprised me most when I took command on November 3 was the flexible options that are in all the plans today. So we actually have very flexible options in our plans. So if something bad happens in the world and there’s a response and I’m on the phone with the Secretary of Defense and the President and the entire staff, which is the Attorney General, Secretary of State and everybody, I actually have a series of very flexible options from conventional all the way up to large-scale nuke that I can advise the President on to give him options on what he would want to do.
    …过去以及我现在所处的位置只是说我们现在的计划,当我11月3日接管指挥权时,其中最让我吃惊的是,在今天的所有计划中都有灵活的选择。因此,我们的计划中实际上有非常灵活的选择。因此,如果世界上发生了一些不好的事情,并且有回应,我正在与国防部长,总统和全体工作人员(包括总检察长,国务卿和所有人)通电话,我实际上有一系列 从传统方式到大规模核武器的非常灵活的选择,我可以建议总统为他提供他想做的选择。
    So I’m very comfortable today with the flexibility of our response options. Whether the President of the United States and his team believes that that gives him enough flexibility is his call. So we’ll look at that in the Nuclear Posture Review. But I’ve said publicly in the past that our plans now are very flexible.
    因此,我今天对响应选项的灵活性感到非常满意。 美国总统及其团队是否相信这给了他足够的灵活性,这是他的要求。 因此,我们将在《核态势评估》中进行探讨。 但我过去曾公开表示,我们的计划现在非常灵活。
    And the reason I was surprised when I got to STRATCOM about the flexibility, is because the last time I executed or was involved in the execution of the nuclear plan was about 20 years ago and there was no flexibility in the plan. It was big, it was huge, it was massively destructive. … We now have conventional responses all the way up to the nuclear responses, and I think that’s a very healthy thing. So I’m comfortable with where we are today, but we’ll look at it in the Nuclear Posture Review again.
    当我来到美国战略司令部(STRATCOM)时对灵活性感到惊讶的原因是,我上次执行或参与执行核计划的时间大约是20年前,而该计划没有灵活性。它很大,它是巨大的,它破坏性很大。 …我们一直有常规的应对措施,直到核响应为止,我认为这是非常正常合理的事情。因此,所以我对我们今天的处境很满意,但我们将在《核态势评估》中再次进行探讨。

During the Trump NPR process, however, the tone changed. Almost one year to the day after Hyten said he was comfortable with the existing capabilities, he told lawmakers he needed a low-yield warhead after all: “I strongly agree with the need for a low-yield nuclear weapon. That capability is a deterrence weapon to respond to the threat that Russia, in particular, is portraying.”
While nuclear advocates were quick to take advantage of the new administration to get approval for new nuclear weapons they said were needed to now respond to Russia’s supposed “escalate-to-deescalate” strategy, efforts to engage Moscow to discuss nuclear strategy and their impact on nuclear arsenals are harder to find. See, for example, this written correspondence between Representative Susan Davis and General Hyten:
虽然核倡导者们很快利用新政府的优势,获得新核武器的批准,但他们表示,现在需要对俄罗斯所谓的“升级到去逐步降级”战略作出回应,而让莫斯科参与讨论核战略及其对核武库的影响的努力则更难找到。例如,见苏珊·戴维斯(Susan Davis)代表和海顿(Hyten)之间的书面信函:
    Rep. Davis: Have you ever had a discussion with Russia about their nuclear posture, and in particular an escalate-to-de-escalate (E2D) strategy, which the Nuclear Posture Review claims is part of Russia’s nuclear doctrine? How did they respond? Do you view this doctrine as offensive or defensive in nature?
    Gen. Hyten: I would like to have such a discussion, but I have never had a conversation with Russia about their nuclear posture.

During the Fiscal Year 2019 budget debate, Democrats argued strongly against the new low-yield W76-2, and opposition increased on Capitol Hill after the 2018 mid-term elections gave Democrats control of the House of Representatives. But given the relatively low cost of the W76-2, and the fact that it was conveyed as merely an “add-on” to an already hot W76 production line, little progress was made by opponents. Reluctantly accepting production of the warhead in the FY 2019 defense budget, opponents again in August 2019 tried to block funding in the FY 2020 defense budget arguing the new warhead “is a dangerous, costly, unnecessary, and redundant addition to the U.S. nuclear arsenal,” and that it “would reduce the threshold for nuclear use and make nuclear escalation more likely.” When the Republican Senate majority refused to accept the House’s sense, Democrats caved.
在2019财年预算辩论中,民主党人强烈反对新的低当量W76-2,在2018年中期选举让民主党控制众议院之后,国会山的反对派增加。但是,鉴于W76-2的成本相对较低,而且它只是作为已经很热的W76生产线的“附加组件”去传送的,竞争对手几乎没有取得什么进展。反对者不情愿地接受2019财年国防预算中的核弹头生产,反对者于2019年8月再次试图阻止2020财年国防预算中的资金,理由是新的核弹头“是美国核武库的危险,昂贵,不必要和多余的补充 ”,并且“将降低核使用的门槛,并使核升级的可能性更大。” 当共和党参议院多数议员拒绝接受众议院的看法时,民主党屈服了。
Just a few months later, the first W76-2 warheads sailed into the Atlantic Ocean onboard the USS Tennessee.

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