Mira Rapp-Hooper

The contours of Donald Trump’s foreign policy are becoming disturbingly clear. Newspapers have labeled his thinking on international affairs "isolationist” and “unabashedly non-interventionist," yet those terms fail to capture the more alarming elements of his philosophy. Trump apparently is prepared to abandon the United States’ most important alliances, even at the risk of those countries acquiring nuclear weapons. In other words, he is prepared to end the decades-long U.S. policy of extended deterrence — protecting close partners against nuclear attack and thereby limiting the spread of nuclear weapons. Moreover, the presidential candidate gives little indication that he understands the implications of these radical policies for global security and stability.

One theme running through Trump’s foreign policy is his disdain for U.S. alliances and allies. In recent news media interviews, he has called U.S. treaties “one-sided," labeled NATO “obsolete” and repeatedly called on South Korea and Japan to contribute more to U.S. basing costs overseas. Trump appeared surprised in a Washington Post interview to learn that allies pay a substantial portion of U.S. overseas basing costs, with none more supportive than Japan. Yet he also seemed unmoved by this information, insisting that allies should pay no less than a full 100% of U.S. overseas costs. A refusal to do so would force a President Trump to begin withdrawing troops, he told The New York Times. When informed this might cause South Korea and Japan to acquire their own nuclear weapons, Trump demonstrated a flippant comfort, stating that the U.S. “may very well be better off.”

It hardly bears noting that abandoning U.S. treaty commitments and acquiescing to nuclear proliferation are completely at odds with decades of U.S. foreign policy. In the darkest days of World War II, American civilian and military leaders identified the merits of establishing a network of overseas bases to allow the United States to address foreign military threats before they could reach the homeland. U.S. planners understood that establishing a forward posture would require cooperation with allies who shared similar security concerns. Furthermore, since shortly after its own use of nuclear weapons against Japan, it has been U.S. policy to oppose any new countries from developing nuclear weapons, be they friend or foe. U.S. presidents have actively opposed allies such as France and Taiwan in their nuclear quests, on the theory that more arsenals would lead to a more dangerous world, no matter who owned the weapons.

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Academic research has borne out the close relationship between U.S. security guarantees and nuclear non-proliferation. Political science studies show that countries under a major power’s “nuclear umbrella” are far less likely to seek their own weapons. The converse holds true: When allies grow acutely concerned about whether their security patron will make good on their treaty promises, they are more likely to seek an independent arsenal. In fact, when the United States began a major troop withdrawal from Asia during the Nixon administration, both Japan and South Korea seriously considered going nuclear themselves, and allied assurance continues to be a significant challenge in East Asia today.

To understand why Trump’s views on extended deterrence are terrifying, one must examine his other positions on nuclear policy and strategy. In a December GOP debate, the candidate appeared to be unfamiliar with the nuclear triad, made up of the intercontinental ballistic missile, submarine-launched ballistic missiles, and bombers that can deliver nuclear weapons to their targets. Just days ago, he refused to rule out the use of a nuclear weapons against the Islamic State terrorist group. In one of the many national security non sequiturs in his Times interview, Trump commented that no one could be sure whether the U.S. nuclear arsenal even worked. This was presumably an allusion to the fact that America observes a de facto moratorium on nuclear testing, but it is contrary to all scientific and technical evidence and a wildly misleading comment at best.

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Perhaps most unsettling, Trump repeatedly insists that the United States must be more “unpredictable” in its national security policy — a chilling assertion, particularly when uttered in such close proximity to such irresponsible nuclear policies. Trump’s naiveté about the world’s most dangerous weapons leads one to infer that he might not have considered the fact that a nuclear Japan and South Korea could lead to dangerous arms racing with China and North Korea, proliferation by other states in East Asia and regional instability that invites major crises.

Trump’s foreign policy interviews might appear to be itinerant ramblings, but on at least one issue, he is crystal clear: He is absolutely not sold on the role that alliances and extended deterrence have played in U.S. global security policy since 1945. Coupled with his erratic nuclear policy positions, this prospective commander in chief’s views are not just irresponsible: They are cataclysmically dangerous.

Mira Rapp-Hooper is a senior fellow with the Asia-Pacific Security Program at the Center for a New American Security. Her Ph.D. dissertation, "Absolute Alliances," was on the role of extended deterrence in international politics.

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