For front-line states like Poland, hosting a stronger ally’s conventional forces bolsters national security in several ways. First, it improves the local balance of power, reducing their vulnerability to more powerful adversaries like Russia. Second, it signifies a commitment from the stronger ally to the weaker ally’s security. By putting troops on its ally’s territory, crises become harder to ignore. Accordingly, with American troops on its soil, Poland will be more confident that the United States would have its back when Russia rattles its saber.
My research addresses why states strive toward, and sometimes back away from, nuclear weapons acquisition when they are already under a superpower’s nuclear umbrella. Drawing on extensive archival and statistical evidence, I find that states as diverse as Konrad Adenauer’s West Germany and Park Chung-hee’s South Korea used American troop deployments as a proxy for whether their nuclear security guarantees were credible.
But in enjoying the benefits of hosting American forces, the loss aversion of allies increases. Thus, when these indicators suggest abandonment, as in the instance of unanticipated troop withdrawal from their own territory, these allies accept greater risk in crafting their defense policies. They become more likely to at least start tiptoeing toward nuclear weapons acquisition. Sometimes they launch nuclear weapons programs in earnest. Sometimes they simply hedge their nuclear bets, as Japan did beginning in the late 1960s.
These indicators of support can even take precedence over other, and arguably better, measures of commitment. West German leaders had known for sometime that the Eisenhower administration’s foreign policy strongly favored nuclear weapons over conventional military power. By the late 1960s, the United States seemed unable to deter North Korean provocations, not the least of which was a failed attack on President Park’s official residence. Yet West Germany and South Korea severely doubted U.S. protection so as to seek nuclear weapons after military withdrawals from their territories began to appear highly probable, if not certain.
If the past is any guide and the return of Cold War dynamics is upon us, then the historical record suggests that it is better to disappoint allies now rather than later. Meeting Central-Eastern European requests for forward deployed troops might reassure allies in the short-run, but it could easily come at the cost of creating false expectations of continued support later. Those countries’ loss aversion also expands.
The risk is that sometime in the future the United States might be unable to support such large-scale deployments. This inability could generate such insecurity among affected allies that drastic actions like nuclear weapons acquisition becomes a real possibility.
Still, one can only speculate how states would react to major and unfavorable withdrawals of military assets from their territories in the 21st century. And indeed, Poland is unlikely to consider nuclear weapons acquisition anytime soon. It is embedded in the European Union, party to the Nonproliferation Treaty, and enjoys the fruits of economic prosperity and successful liberal democracy. Yet the current absence of proliferation concerns should not inspire complacency today. Russian efforts at annexing Crimea show that what seems so unthinkable one moment can become a fait accompli the next.
Instead of granting such requests as Poland’s, the United States should opt for alternative ways to signal reassurance. Tightening military coordination within NATO, institutionalizing transfers of defensive weapon systems to Central-Eastern European allies, planning and executing joint military exercises and verbally renewing pledges of commitment and diplomatic support are important tools that can inspire confidence. These actions also grant the United States more flexibility in its efforts to find a diplomatic solution that takes into account Russian concerns regarding NATO encirclement.
These tools are imperfect, but they may be sufficient in assuaging fears that the United States stands aloof from the security interests of its allies in Central-Eastern Europe. Certainly, they create fewer risks than those associated with pulling out American troops later.