氫彈震散戰略平衡 國際社會需要Plan B

<轉載自2017年9月5日 明報 社評>

朝鮮宣布成功測試氫彈，威力之大足以瞬間夷平一座城市，標誌朝鮮已擁有強大核子震懾力，韓國政府相信朝鮮已成功將核彈微型化，可以由洲際導彈發射。半世紀前中國成功發展「雙彈一星」的歷史，今時今日在朝鮮半島重演，再爭論朝鮮核武器是否可靠、是否有能力攻擊美國本土，否認朝鮮是核武國家，只是自欺欺人。今次核試成為改變東北亞博弈規則的分水嶺（game changer），雖然觸發戰爭風險仍然不大，然而有可能在區內引發連鎖效應，中美俄必須借鑑歷史，審慎處理，否則只會令東北亞更趨動盪。

朝鮮擁核貨真價實 中美需阻連鎖效應

過去朝鮮核試又或試射導彈，美國政府和西方專家經常大潑冷水，質疑試驗失敗，可是今次朝鮮核試產生的地震波，相當於6.3級地震，威力是對上一次核試的10倍，美國軍事專家普遍認同，有必要假定朝鮮的確擁有氫彈。回顧美蘇中國發展核武經驗，到了第5次核試，3國大抵都已掌握氫彈技術。今次是朝鮮第6次核試，成功引爆氫彈，從武器發展角度來看，並未叫人太意外。

近年朝鮮決意發展核武，中朝再非「血盟」關係。中國舉行金磚五國峰會，朝鮮試爆氫彈，完全不給中國面子。外交部除了嚴辭譴責，也向朝鮮駐北京大使館提出嚴正交涉，情形一如過去數次對朝鮮核試的反應，反映北京仍傾向審慎行事，會否有進一步強硬動作，仍屬未知之數。今年初，中國提出「雙暫停」，呼籲美國與朝鮮對話甚至提供援助，換取朝鮮暫停核試和彈道導彈試射，一些美國學者也認為方案值得考慮，然而華府錯過時機，現在朝鮮成功試爆氫彈，擁有直轟美國本土的洲際導彈指日可待，「雙暫停」的作用大打折扣，充其量可以阻止測試洲際導彈，惟已不能逆轉朝鮮掌握核彈氫彈技術這一現實。

雖然美國總統特朗普沒有排除動武，不過美國攻打朝鮮的機率仍然相當低。誠然，朝鮮核武數量有限，按照核震懾軍事理論，並未具有「第二擊」（second strike）的核子報復能力，然而就算美國先發制人，以「外科手術式打擊」摧毀朝鮮大部分核設施，甚或擊殺金正恩，也不能阻止朝鮮報復，以密集火炮和常規武器將首爾變成火海；至於美軍全面入侵朝鮮的可能更是零，華府不可能冒險挑起一場核戰。

當前最大危機並非美朝戰爭一觸即發，而是朝鮮成為貨真價實的核武國家，將動搖東北亞軍事戰略平衡，加深地區安全威脅。因應朝鮮確立核震懾力，區內所有國家勢將調整外交軍事策略，尋求新的勢力平衡，連鎖效應悄然發生。韓國政府已表明願意落實部署餘下的美國薩德導彈防禦系統，還會尋求美軍長駐航空母艦，華府不會輕易放棄這個增兵東北亞牽制中國的機會，然而這又必然刺激中俄神經。昨天俄國副外長雷雅布可夫強調，為保持軍事平衡，需要回應美國在韓國擴大導彈盾系統。至於日本方面，國內右派也可能蠢蠢欲動企圖發展核武，或明或暗試探美國反應。中美是朝核危機兩大要角，必須沉着應對，不能讓連鎖效應失控。

當年接受中國擁核 美國必須面對現實

有西方專家指出，朝鮮發展核武的過程，與1960年代中國發展「雙彈一星」（核彈、導彈和人造衛星）相似。當年毛澤東發展核武，一大原因是中蘇鬧僵，中國感到孤立，又要應付美國核威脅；刻下朝鮮發展核武，大背景是中國放下意識形態包袱，與韓國修好，跟華府合作，平壤陷入孤立，愈益擔心國家安全。當年甘迺迪和詹森政府對中國發展核武相當忌憚，華府曾考慮先發制人攻擊，結論是不可行。華府採取一系列手段阻止中國核計劃無果，最後只好接受中國擁有核武，調整策略適應。中國擁有核震懾力之後，日本、台灣和韓國均曾躍躍欲試，企圖發展核武，美國的策略是一邊大力制止，一邊強調為區內盟友提供核保護傘。後來中美破冰，中國走上開放改革之路，融入國際社會，西方談論中國核武威脅也漸漸減少。

朝鮮半島無核化仍然是Plan A，不應輕言放棄，惟事態發展至今，各方恐怕都要有兩手準備，接受朝鮮擁有核武的現實，一如當年接受中國擁核一樣。朝鮮漠視聯合國要求，必須懲罰制裁，然而若要釜底抽薪，美國還須與朝鮮展開談判，避免輕舉妄動刺激地區軍事形勢，更不能容許區內盟友染指核武。華府繼續向中國打主意，威脅制裁與朝鮮有生意來往的中國企業，不會令平壤放棄核武，只會加劇中美摩擦，令朝鮮漁人得利。中美俄需要盡快磋商框架，令東北亞局勢穩定下來，防止連鎖效應失控，同時研究是否需要有Plan B﹕如何令朝鮮成為一個負責任的核武國家。

Plan B needed as hydrogen bomb has upset strategic balance in Northeastern Asia

THE North Korean government has announced that it successfully tested a hydrogen bomb powerful enough to raze a city to the ground within seconds, signalling that North Korea is now a country with great nuclear deterrents. The South Korean government believes that North Korea has found success in miniaturising its nuclear warheads and fitting them to an intercontinental ballistic missile.

In the past, whenever North Korea conducted a nuclear test or test launched its missiles, the US government and experts in the western world would shrug it off and argue that the tests had ended in failure. This time around, the tremors caused by the North Korea nuclear test were equivalent to a 6.3-magnitude earthquake, and were ten times as powerful as those from the previous nuclear test. There is a consensus among US military experts that it is necessary to assume that North Korea is indeed equipped with hydrogen bombs. Looking back at the paths taken by the US, the Soviet Union and China in their development of nuclear weapons, we can see that the three countries largely possessed hydrogen bomb technology after their respective fifth nuclear tests. As North Korea has just conducted its sixth nuclear test and has successfully detonated a hydrogen bomb, the development, from the perspective of nuclear science, is not very surprising.

In recent years, North Korea has been determined to develop nuclear weapons, and is no longer in a "relationship sealed in blood" with China. North Korea detonated a hydrogen bomb just when China was hosting the BRICS summit, showing complete disregard for China. The Chinese foreign ministry condemned the nuclear test in strong terms and lodged stern complaints to North Korea's embassy in Beijing — just as how it reacted to North Korea's nuclear tests in the past. This shows that the Beijing authorities still incline to act prudently, so much so it is questionable whether there will be tougher actions from them. Early this year, China proposed a "double-freeze" strategy, calling on the US to resume dialogue with North Korea — and even provide it with aids — in exchange for North Korea halting its nuclear tests and ballistic missile tests. Some American experts also believed that the proposal was worth consideration. But the White House missed the opportunity to do so. Now that North Korea has successfully detonated a hydrogen bomb, it is only a matter of time before North Korea possess intercontinental ballistic missiles capable of hitting US soil directly. Such being the case, there is much less the "double-freeze" proposal can achieve. The most it can do is prevent North Korea from test-launching its intercontinental missiles. It cannot change the fact that North Korea now possesses hydrogen bomb technology.

Though US president Donald Trump has not ruled out the possibility of a military operation, it is still very unlikely that the US will strike North Korea. True, due to the limited number of its nuclear weapons, North Korea, according to theories of nuclear deterrence, does not have the ability to carry out a "second strike", i.e. to retaliate against a nuclear attack with one of its own. However, even if the US launches a pre-emptive attack, destroys most of North Korea's nuclear weapons "surgically" or even takes Kim Jong Un's life, it will not be able to prevent North Korea's reprisal — turning Seoul into a sea of fire with heavy artillery fire and conventional weapons. The possibility of an all-out invasion of North Korea is zero, as the White House cannot afford starting a nuclear war.

If the White House continues to take advantage of China by threatening to slap sanctions on Chinese enterprises that do business with North Korea, it will not be able to make North Korea give up its nuclear weapons. It will only intensify Sino-US disagreements, and North Korea will profit from the situation. China, the US and Russia should negotiate a framework as soon as possible to stabilise the situation in Northeastern Asia and prevent things from spiralling out of control. They should also study the necessity of a Plan B — making North Korea a responsible nuclear-armed country.

氫彈震散戰略平衡 國際社會需要Plan B

朝鮮宣布成功測試氫彈，威力之大足以瞬間夷平一座城市，標誌朝鮮已擁有強大核子震懾力，韓國政府相信朝鮮已成功將核彈微型化，可以由洲際導彈發射。

過去朝鮮核試又或試射導彈，美國政府和西方專家經常大潑冷水，質疑試驗失敗，可是今次朝鮮核試產生的地震波，相當於6.3級地震，威力是對上一次核試的10倍，美國軍事專家普遍認同，有必要假定朝鮮的確擁有氫彈。回顧美蘇中國發展核武經驗，到了第5次核試，3國大抵都已掌握氫彈技術。今次是朝鮮第6次核試，成功引爆氫彈，從武器發展角度來看，並未叫人太意外。

近年朝鮮決意發展核武，中朝再非「血盟」關係。中國舉行金磚五國峰會，朝鮮試爆氫彈，完全不給中國面子。外交部除了嚴辭譴責，也向朝鮮駐北京大使館提出嚴正交涉，情形一如過去數次對朝鮮核試的反應，反映北京仍傾向審慎行事，會否有進一步強硬動作，仍屬未知之數。今年初，中國提出「雙暫停」，呼籲美國與朝鮮對話甚至提供援助，換取朝鮮暫停核試和彈道導彈試射，一些美國學者也認為方案值得考慮，然而華府錯過時機，現在朝鮮成功試爆氫彈，擁有直轟美國本土的洲際導彈指日可待，「雙暫停」的作用大打折扣，充其量可以阻止測試洲際導彈，惟已不能逆轉朝鮮掌握核彈氫彈技術這一現實。

雖然美國總統特朗普沒有排除動武，不過美國攻打朝鮮的機率仍然相當低。誠然，朝鮮核武數量有限，按照核震懾軍事理論，並未具有「第二擊」（second strike）的核子報復能力，然而就算美國先發制人，以「外科手術式打擊」摧毀朝鮮大部分核設施，甚或擊殺金正恩，也不能阻止朝鮮報復，以密集火炮和常規武器將首爾變成火海；至於美軍全面入侵朝鮮的可能更是零，華府不可能冒險挑起一場核戰。

華府繼續向中國打主意，威脅制裁與朝鮮有生意來往的中國企業，不會令平壤放棄核武，只會加劇中美摩擦，令朝鮮漁人得利。中美俄需要盡快磋商框架，令東北亞局勢穩定下來，防止連鎖效應失控，同時研究是否需要有Plan B﹕如何令朝鮮成為一個負責任的核武國家。