Consider the ongoing war in Europe. Beginning in December 2021, US President Joe Biden warned Russian President Vladimir Putin that if Russia attacked Ukraine, it would face new harsh sanctions - but to no avail. Then, when the United States and its European allies thwarted Russia's plans by arming Ukraine, Putin began rattling off nuclear weapons. But the help of the West did not weaken even then.
Was deterrence successful or not? Answering this question is a difficult task because it requires an assessment of what would have happened if there had been no threat. It is difficult to prove otherwise. If I hang the sign "No elephants allowed" on the front door and there are no elephants in my house, have I deterred them? It primarily depends on the probability that literate elephants appear.
The war in Ukraine shows that reducing risk is not always an either-or choice, but often a matter of degree. Perhaps Putin, counting on a shaky alliance with the West, thought the sanctions would not work. However, he has so far refrained from attacking NATO supply lines. And while the West, for its part, continues to arm Ukraine despite Putin's nuclear-rattling, it is reluctant to provide longer-range missile systems or modern fighter jets.
Deterrence requires trust: threatening a maximum response to protect smaller interests breeds distrust. And especially when a nuclear power promises to extend its umbrella to defend a distant land.
During the Cold War, the USA and the USSR convincingly extended their nuclear deterrence to Western and Eastern Europe, respectively. While some analysts were skeptical that the US would risk New York to protect the isolated enclave of West Berlin, the threat worked, in part because of the US troops stationed there. Although the so-called "Berlin Brigade" was too small to defend against a Soviet invasion, it ensured that a nuclear attack on the city would result in American casualties. (At the same time, American forces in Europe, both nuclear and conventional, were not a reliable deterrent to Soviet military intervention in Hungary in 1956 or Czechoslovakia in 1968.)
This story is also relevant to the current situation in Korea - North Korea has nuclear weapons, and South Korea remains bound by the Nuclear Non-Proliferation Treaty. One of the latest polls showed that more than 70 percent of South Koreans are in favor of creating their own nuclear arsenal in the country. Instead, South Korean and U.S. Presidents Jun Suk-yeol and Joe Biden agreed during their April meeting that the U.S. would deploy a nuclear submarine near the Korean Peninsula and expand consultations with South Korea on nuclear and strategic planning, similar to how the United States interacted with NATO allies during the Cold War. war.
The credibility of extended American deterrence in this case, as in the Berlin example, is enhanced by the presence of 28.500 American troops in South Korea. The two countries are locked in a "fated union" because North Korea cannot attack South Korea without Americans getting killed at the same time. Advanced bases in Japan give the same guarantee. This is why former US President Donald Trump's frequent musings about withdrawing troops from places like Japan and South Korea were so disastrous.
Trump's presidency has also highlighted the ineffectiveness of nuclear intimidation and bribery. When North Korea successfully tested an ICBM in 2017, Trump threatened "fire and fury like the world has never seen," but to no avail. Then he tried direct diplomacy. After meeting North Korean dictator Kim Jong Un in 2018 — a long-cherished foreign policy goal of the North — he brazenly predicted the imminent demise of the country's nuclear program. No one was surprised that North Korea did not disarm. In Kim's view, his reputation and the fate of his family dynasty depend on nuclear weapons.
The example of Taiwan, which China claims as its territory, shows how changing circumstances can challenge tried and tested containment strategies. When Presidents Richard Nixon and Mao Zedong met in 1972 to restore US-China relations, they disagreed on the status of Taiwan. In the end, both sides developed a formula to delay the issue: the US recognizes "one China", the People's Republic on the mainland, and also recognizes that the people on both sides of the Taiwan Strait are Chinese. The United States has provided arms to Taiwan under the Taiwan Relations Act, but has not recognized it as a sovereign country.
For years, the United States refused to say whether it would defend Taiwan. When I was in Beijing as a representative of the Pentagon in the Clinton administration, the hosts asked me if our countries would go to war over Taiwan. I replied that no one could know, noting that although Secretary of State Dean Acheson did not include South Korea in the US defense perimeter in his January 12, 1950 speech, the US entered the Korean War just six months later. Invoking what deterrence theorist Thomas Schelling called "the threat that leaves something to chance," I warned the Chinese not to test us.
What some call a policy of "strategic uncertainty" might better be described as a "double deterrent," designed not only to prevent China from using force against the island, but also to deter Taiwan from de jure independence. Now some analysts worry that this strategy is weakening as China's military power grows and more US lawmakers visit Taiwan. Biden has said four times that the United States will defend Taiwan, but the White House has responded each time with a statement affirming his commitment to the "one China" policy. In this context, to prevent total war, it will be crucial to choose a path that will allow one to avoid showing weakness or provoking escalation.
History reminds us that assessing the success of deterrence can be difficult. There are a number of factors, such as trust, that are key to achieving the desired results. But as deterrence dilemmas continue to evolve and multiply, studying the limitations of strategies is equally important to finding approaches that will work.
The author is a professor at Harvard; he was the US Assistant Secretary of Defense
Copyright: Project Syndicate, 2023. (translation: NR)
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