【文/观察者网专栏作者 周波】

没有人知道俄乌冲突还会持续多久，但所有人都知道，最可怕的梦魇是俄罗斯决定使用战术核弹。俄罗斯领导人曾多次暗示过这样的想法。现在，连卡拉加诺夫（Sergei Karaganov）和特列宁（Dmitri Trenin）这样的俄罗斯著名学者也开始鼓噪核战，呼吁对北约国家（如波兰）发动战术核武器袭击，以“瓦解西方的意志”，让他们相信俄罗斯的核威胁绝非虚张声势。

如果俄罗斯使用核武器的威胁确实只是虚张声势，那么这种策略已经奏效，毕竟，外界争论俄罗斯是否会使用核武器，本身就是威慑成功的体现。但如果这不是虚张声势呢？西方正在蚕食自己的红线，许多它们一开始声称不会输送的武器，现在已源源不断输送给基辅。

既然如此，大家凭什么确信俄罗斯就不会最终使用核武器呢？现在，俄乌战场陷入僵局，连莫斯科也遭到乌克兰多次无人机袭击；乌克兰总统泽连斯基还声称战争正在“重返俄罗斯”。

要想消除人类可能面临的这一巨大浩劫的威胁，我们也许可以另辟蹊径：中国和美国达成不首先使用核武器的协议，英国、法国随后加入，俄罗斯最后一并加入。这有过先例：1998 年印巴核试验后，中美两国罕见地团结一致， 迅速发表联合声明，宣布不再将核武器瞄准对方。这促使五个核大国家于2000年发表联合声明，宣布它们的核武器不针对彼此或其他任何国家。

2022年1月，也就是俄乌冲突爆发前一个月，五个核大国发表联合声明，一致认为“核战争打不赢也打不得”。既然核战争确实无法打赢，那么他们为什么就不能承诺不首先使用核武器呢？不首先使用核武器，并不排除核反击的选择，因此也不会削弱核大国的威慑能力。

俄罗斯装备的“伊斯坎德尔”战术弹道导弹，既可以使用常规弹头，也可以使用核弹头。图自路透

对中国而言，自1964年首次核试验成功以来，不首先使用核武器是一贯政策。因此，这一历久弥新的政策，不会因为中俄友谊而改变。拜登政府宣称，美国只会“在极端情况下考虑使用核武器，以捍卫美国或其盟国和伙伴的重大利益”，这一政策与中国的政策其实相去不远。

美国比其他任何国家都更有“本钱”承诺不首先使用核武器。美国拥有压倒性的常规军事力量的优势，几乎没有美国用常规军事武器无法完成的任务。

美国需要核武器来保卫盟友的说法也值得商榷。事实拥核的朝鲜，是迄今为止唯一一个不断进行核讹诈的国家，甚至在新法律中正式宣布会先发制人进行核打击。但这只是一种吸引眼球的策略。除非金正恩政权岌岌可危，否则很难想象他会对韩国或日本发动自杀式核打击，因为这必将招致毁灭性的报复。整个朝鲜半岛只有1100公里长，挥之不去的放射性尘埃将把任何胜利化为灰烬。

2001年，俄罗斯和中国达成协议，约定不首先对对方使用核武器。如果中国和美国能达成类似协议，那么美国的盟国英国和法国也完全可能与中国达成同样的协议。

最大的挑战是，如何说服俄罗斯加入这一协议，不过这并非完全不可能。 普京应该知道， 核武器并不能实质性改变战争局面。即便核武器貌似威力无比，它们也没有帮助美国赢得越战、伊拉克战争和阿富汗战争，或帮助苏联赢得阿富汗战争。现在，俄罗斯的核武器也没能消磨乌克兰的强烈抵抗。

这或许就是为什么，普京只隐晦暗示而从未公开威胁使用核武器。相反，他在习近平主席3月访俄的中俄联合声明中重申“核战争打不赢也打不得”。

如果美国领导的北约最担心普京或将使用核武器，那么他们就需要为普京提供一个台阶，即北约先承诺在任何情况下都不首先对俄罗斯使用核武器。这对北约来说完全可以承受：北约是世界上最大的军事同盟，拥有31个成员国、3个核武器国家，其常规军事力量远超俄罗斯，很难想象它为什么要首先对俄罗斯发动核打击。

化解欧洲核威胁的终极之道，或许还在于北约想所不能想， 即承诺在瑞典加入后不再扩员。北约成员仅限于欧洲国家，在瑞典加入之后，还在排队的国家已寥寥无几，等待加入的国家只有三个，即波黑、格鲁吉亚和乌克兰。

显然，波黑不会明显增强北约的军事实力；格鲁吉亚已经与俄罗斯发生了战争，部分原因就是格鲁吉亚希望加入北约。没有人知道俄乌冲突将如何结束，但北约不需要扪心自问就应该知道，与一个核大国进行“永远的战争”是致命的危险。

英文原文：

No one knows how long the war in Ukraine will last. But everyone knows the worst nightmare is Russia decides to use a tactical nuclear bomb. Russian leaders have repeatedly hinted at this. Now some prominent Russian scholars such as Sergei Karaganov and Dmitri Trenin have joined the choir. They called for tactical nuclear weapons attacks on a NATO country, say, Poland, to “break the will” of the West and convince it that Russia’s nuclear threats are not a bluff.

If Russia’s warning on using nukes is a bluff, this tactic has already worked in that letting people mulling over if Moscow will use nuclear weapons or not is successful deterrence itself. But what if this is not a bluff? The west is nibbling away its own redlines, however gradually, by sending more and more sophisticated weapons to Kyiv that were considered taboos in the beginning, so why one can rest assured that Moscow won’t use nuclear weapons, eventually? The battlefield is in a stalemate.

Kyiv’s drone attacks were found in Moscow. Ukrainian President Zelensky warned that the war is “returning to Russia”.

Now that the threat of an unspeakable horror against humanity looms larger, perhaps a short-cut is China and the US reaching an agreement of no first use of nuclear weapons that will be joined by Britain and France and finally, Russia. Here is a lesson learnt. In the wake of the Indo-Pakistan nuclear tests in 1998, in a rare move to show solidarity, China and the US quickly came to a joint declaration of de-targeting their nuclear weapons against each other. This led to a joint statement among the five nuclear-weapon states in 2000 that their nuclear weapons are not targeted at each other or at any other states.

Similarly, in a joint statement issued by the five nuclear powers in January, 2022 -- a month before Russia’s invasion of Ukraine, they agreed that “a nuclear war cannot be won and must never be fought”. If indeed a nuclear war cannot be won, then why can’t they pledge no first use of nukes in the first place? No first use doesn’t exclude nuclear retaliation; therefore, it won’t neutralize a nuclear power’s ability in deterrence.

For China, no first use of nuclear weapons is an iron-clad policy since its detonation of a nuclear device in 1964. Therefore, such a time-honored policy won’t change because of its rapprochement with Russia.  The Biden administration declared that it would only “consider the use of nuclear weapons in extreme circumstances to defend the vital interests of the United States or its allies and partners.” Such a policy is not so far away from that of Beijing.

The US can afford to make a no first use commitment more than any other countries. Today, the United States has overwhelming conventional military superiority. One can hardly cite a mission that the United States could not accomplish with conventional weapons.

The assertion that US needs nuclear weapons to defend its allies is questionable too. So far, DPRK- a de facto nuclear weapon state, is the only country that has repeatedly played with nuclear blackmails. It has even officially declared to use preemptive nuclear strikes in a new law, but this is a strategy of drawing attention. Unless the survival of Kim Jong-un ’s regime is in jeopardy, it is hard to understand why he would launch a suicidal nuclear attack on South Korea or Japan that will surely invite devastating retaliation. The whole Korean peninsula is only 1100 kilometers. The lingering radioactive dust will make any victory meaningless.

In 2001, Russia and China agreed not be the first to use nuclear weapons against each other. If Beijing and Washington agree on no first use, then it is entirely possible for Britain and France, two American allies, to reach the same deal with China.

The challenge is how to get Russia in, but it is not entirely impossible. President Putin should know nuclear weapons are not really game changers. No matter how formidable they seem, they didn’t help the US in Vietnam, Iraq, and Afghan wars. They didn’t help the Soviet Union in Afghan war. They haven’t helped Russia in mitigating Ukraine’s strong resistance against Russia’s invasion, either.

This probably tells why in spite of his thinly-veiled hints, Putin has never overtly threatened to use nuclear weapons. Instead, he reiterated in a China-Russia joint declaration during President Xi Jinping’s visit to Moscow in March that “a nuclear war cannot be won and must never be fought”.

If the deepest concern of the US-led NATO is Putin might eventually resort to use of nuclear weapons, it needs to offer him an off-ramp, that is, NATO unilaterally promise no first use against Russia in any circumstances now. This is affordable for NATO. The largest military alliance in the world has 31- member states, three nuclear weapon states and its conventional forces far outnumber that of Russia. It is hard to imagine why it should launch a nuclear strike on Russia first.

Perhaps the final solution to defuse nuclear threats in European continent lies in NATO’s thinking of the unthinkable: a pledge of no further expansion after Sweden joins NATO. NATO membership is confined to European countries. After Sweden’s entry into NATO, there aren’t many countries queuing in line anyway. Only three countries, namely, Bosnia and Herzegovina, Georgia and Ukraine are found on the waiting list.

Apparently, Bosnia and Herzegovina won’t add much weight to the military strength of NATO. Georgia already had a war with Russia, in part because of its wish to join NATO. At a time when no one can tell what is the endgame, NATO doesn’t need soul searching to know a “forever war” with a nuclear power is lethally dangerous.

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