Throughout the Cold War, while these five states remained committed to Western political values and economic systems, they found a neutral status more compatible with their histories and contemporary interests.

For Switzerland and Sweden, neutrality had particularly deep roots. Both decided that a formal position of military neutrality would serve their interests in the Cold War as it had before.

Finland's Cold War neutrality reflected the country’s geographic proximity to the Soviet Union and its vulnerability to Soviet military power and political influence.

Austria became neutral as the outcome of its struggle to regain sovereignty after World War II, granted only in 1955 by the Austrian State Treaty following years of Soviet foot-dragging.

Ireland had been willing in 1949 to negotiate a bilateral defence pact with the United States, but opposed joining NATO until the Northern Ireland question with the United Kingdom was resolved. Subsequent Irish neutrality was therefore based primarily on Irish issues problems with the UK, not on Cold War confrontation. Under the circumstances, Ireland effectively got a free ride on defence as NATO would have been forced by self-interest to defend Irish territory in any case.

In 1997, my Congressional Research Service report on “NATO Enlargement and the Former European Neutrals,” speculated that at least a few of these countries would have to figure out what “neutrality” meant for them in the new circumstances. The report concluded that “… the rules of the game in Europe have changed so substantially that old concepts of neutrality have ceased to be relevant as a framework for the interests and policies of these five countries.”

However true that may still be over 20 years after the end of the Cold War, none of the five have sought NATO membership. This, in spite of the fact that all non-Soviet former members of the Warsaw Pact and the three former Soviet Baltic Republics have long since joined the Alliance.

NATO’s Partnership for Peace (PfP) programme made it possible for each of these five countries to cooperate with the Alliance on their own terms while not becoming a member. By the end of the 1990s, all had joined the PfP. Switzerland joined even before becoming a member of the United Nations.

After joining the PfP, all five countries were challenged to give their membership meaning in terms of both NATO’s operations and their foreign and defence policies. And, since the late 1990s, all five countries have adjusted their international roles to play relevant and, in some cases, important roles in support of NATO’s missions.

The security policies underlying the continued “neutral” or non-aligned postures of these countries are influenced by two key factors: external ones, including membership in the European Union (EU) and the general security situation in Europe, and internal political dynamics.

Membership in the EU of all five except Switzerland has strongly influenced their choices. The EU agreement to develop a common security and defence policy (CSDP) following the 1998 Franco-British St-Malo summit perhaps mitigated the view that the former neutrals were free-riding on the NATO’s security guarantee. Active participation in development of the CSDP provided more focus and some rationale for the defence efforts made by these countries.

To some, the CSDP provided a preferable framework for their defence efforts. The Austrian Foreign Ministry still describes Austria’s partnership with NATO as a logical consequence of its EU membership. The argument is that Austria’s participation in PfP is crucial for its full involvement in the military aspects of the European Security and Defence Policy (ESDP) as there is an overlap of 21 countries in the two areas.

Sweden could be seen as the most enthusiastic contributor to NATO missions, and possibly the one that has edged closest to actually joining. The perception that an unreformed Russia presented a growing threat combined with a feeling that the EU’s CSDP might be insufficient security insurance could yet instigate a Swedish application to join.

Finland might be seen as the next “most likely to join,” if only because the general view in the region is that should Sweden decide to apply for membership, a Finnish application would not be far behind. The same two external factors influencing Sweden – concerns about Russia and EU insufficiency – would weigh heavily on Finland’s decisions.

The relevance of Ireland’s troubled relationship with the UK has diminished over time, particularly following the 1998 Northern Ireland settlement. But nothing suggests NATO membership has become more likely. There is a residue of nationalist sentiment in Irish politics that still resists closer NATO ties and even enhanced military cooperation in the EU. Ireland, however, has remained an active partner in spite of this and its recent financial crisis.

Unlike Ireland, no strong historical enmity has kept Austria out of the Alliance. The main Austrian political parties are split on the question, with the Social Democrats (SPÖ) against and the Christian Democrats (ÖVP) more favorably inclined. The fact that Austrian neutrality had strong roots in Cold War confrontation would suggest the logic of abandoning the status. However, the late Social Democratic Chancellor Bruno Kreisky (1970-1983) elevated Austria’s neutral status to the point where neutrality became a mythical part of the Austrian identity. That “myth” persists in 2013.

Switzerland is perhaps the furthest away from seriously considering joining NATO. Its neutrality was chosen, not imposed, when granted by the Congress of Vienna in 1815. This status has given the Swiss Confederation a special role in international relations that the Swiss will not likely abandon under most foreseeable circumstances.

For all of these countries, partnership with NATO can be seen as a successful hedging strategy. True, partnership does not come with the Article 5 collective defence protection that membership awards. But it also does not come with any of the burdens of membership.

When the United States complains about inadequate burdensharing, these countries escape guilty status and can even point proudly to their voluntary contributions to NATO missions. Levels of defence spending in these countries are certainly no more impressive than those of many European NATO members. But their contributions are seen as a “plus,” made by free will and well-appreciated.

In the post-Afghanistan era, decisions by NATO members to expand cooperation on cybersecurity and other non-kinetic security efforts would enlarge the field on which the former neutrals can play. Although Sweden and Finland have strong military traditions, the other three countries are most likely to contribute when the guns have fallen silent. This may be seen by some NATO governments as insufficient. But it may be the way in which the very special security circumstances and policies of these “formerly neutral, now non-aligned nations” can co-exist with more intensive partnership relations.