During the late 1960s world politics moved into a gradual relaxation of tension. The Soviet Union, after its violent suppression of the Prague Spring in 1968, unopposed by the US-led West, declared the Brezhnev Doctrine whereby all the advances of socialism in Europe would be aggressively defended. The US administration of Richard M. Nixon that took office in 1968 initiated a diplomatic process with the Soviet Union aimed at limiting strategic nuclear weapons in order to slow down the nuclear arms race. In 1972 the first treaty concerning limitations of the number of stra tegic nuclear missiles (SALT I) was agreed upon. It was supported by the ABM Treaty, the ban on comprehensive systems of defence against missiles, which aimed to ensure strategic stability through maintaining mutual vulnerability vis-à-vis a nuclear strategic attack.

With a modicum of strategic stability and the Brezhnev Doctrine keeping a lid on oppositional tendencies in the Soviet sphere of influence, political premises made it possible to negotiate and agree by the mid-1970s on the multifaceted Helsinki Final Act of the Conference on Security and Co-operation in Europe. This led to a provisional form of regional stability. However, internal forces in Eastern Europe, including in the Soviet Union, started to draw upon the human dimension provisions of the document in order to demand reform and respect for human rights. These challenges grew during the 1980s and contributed to undermining the legitimacy of the Soviet system and to its ultimate collapse by the end of the decade.

Well before that, the Soviet invasion of Afghanistan in 1979 had abruptly halted the tentative strategic détente and brought the superpower relationship to its most strained level since the 1960s. Not until the mid-1980s, with the arrival of Mikhail Gorbachev to the leadership in Moscow, did the superpower relationship return to what could be called normality.

A marginal but not insignifi cant contribution to that normalization became the relative success of the 1984-86 Stockholm Conference on Confidence- and Security-Building Measures in Europe.

However, already in the late 1970s the Soviet Union had provoked a major crisis at the Euro-strategic level with its development of intermediate-range nuclear missiles (SS-20s) capable of reaching targets in Western Europe. The question of a Western response through a deployment by NATO of cruise missiles and Pershing II ballistic missiles created a deeply divisive political conflict inside many NATO countries in Europe, even costing one head of government, Helmut Schmidt, his job in the Federal Republic of Germany.

The standard and reflexive thought pattern of seeing international security as a binary zero-sum game had to be broken with the collapse of the Soviet system. Governments, academics, journalists and think tanks scrambled to define new paradigms as political configurations changed, implying formidable challenges for international diplomacy and security. With the advent of the 21st century a different set of actors came into play as international terrorists added to the other challenges implied by the globalization of the worlds of politics, economy and society.

All these developments obviously had a profound impact on SIPRI's research activities. Given the concern for the nuclear arms race in the late 1960s and early 1970s, research attention was focused on nuclear testing, verification and the potential for nuclear disarmament. As Jan Prawitz points out, SIPRI established already in the beginning of its existence unparalleled records of nuclear explosions, as seismically identified, as well as of available data on disarmament and armaments matters.

With regard to chemical and biological weapons (CBW), SIPRI made a singular contribution to international disarmament already from the outset with the publication from 1971 of a series of studies on such weapons. This research, unique in scope and quality, came to constitute a scientific base for the preparation for the multilateral disarmament negotiations in Geneva on a chemical weapon ban. When, at last, substantive diplomatic negotiations could start in the 1980s, a generation of experts from countries outside the group of major CBW possessor states were equipped to turn the talks into genuinely multilateral negotiations, which proved ultimately successful when in the 1990s a convention banning chemical weapons was agreed upon.

Without in any way diminishing its continuing research focus on weapons of mass destruction, in the early 1980s SIPRI put considerable attention and research engagement into the issues at stake in European regional security and armaments disputes. Not only through the interests of director Frank Blackaby, but also with the recruitment to the Governing Board of Egon Bahr, the architect of Bonn's Ostpolitik, and Emma Rothschild, associate of the Independent Commission on Disarmament and Security Issues, chaired by Olof Palme, the concept of Common Security became part of the SIPRI identity. As described by Emma Rothschild in her essay in this volume, a SIPRI symposium in 1983 launched the concept that is now an element of mainstream doctrine. Common Security was presented as something of an alternative to regional nuclear weapon deployment in Europe. Thus, without in any way being formally linked to the European nuclear dis armament movements (European Nuclear Disarmament, END, and Campaign for Nuclear Disarmament, CND), SIPRI became widely seen as a sympathetic player and part of the wider culture of the non-nuclear movement in Europe at that time.

With the arrival in 1986 of a new director, Walther Stützle-a former close associate of Helmut Schmidt-it was not surprising that SIPRI shifted direction and quickly distanced itself from the European disarmament movements. The new direction was the easier to implement as the INF Treaty of 1987, banning all disputed missiles, had weakened the motivation and mass appeal of the disarmament movement.

This does not mean that the shift pursued by the new director did not create some anxiety within SIPRI. However, the turn of policy in a more 'metallic' direction, focusing on issues of balance of conventional forces in Europe and the subsequent reductions process (the CFE Treaty) as well as the follow-up to the moderately successful Stockholm Conference on Confidence- and Security-Building Measures in Europe of the mid-1980s, turned out to be timely and well matched to international demands. SIPRI's quick adjustment to the new realities in Europe and in world politics served the status of the Institute well and positioned it to react proactively to the dramatic changes ushered in with the end of the Soviet system.

When it came to the task of defining a role for SIPRI in the world of the post-cold war era, the Institute was again blessed with a director with the intellectual and conceptual powers to match the challenge. Adam Daniel Rotfeld succeeded in finding and understanding long-term trends amidst the tumultuous developments emerging from the ruinous, discredited and corrupt remnants of communist practices in Europe. Building upon the SIPRI fundamentals of providing optimal transparency in arms production, military expenditure and arms trade, and its continuous insight into arms control matters, the Institute was able to make strong contributions to the Europe-wide debates on a new security architecture.

With the millennium shift, the move from national, via regional, to global security became a reality. Advances in globalization ushered in not only new challenges for the international community in its management of international security, but also and ominously a new phenomenon, the non-state actor as a terrorist. SIPRI's new director from 2002, Alyson J. K. Bailes, has succeeded in harnessing her combination of outstanding diplomatic experience and conceptual creativity to steer the Institute to the very top rank in Europe in proposing, articulating and also executing policies and answers to the global challenges.

Paradoxically enough, she has at the same time-and probably more so than any of her predecessors-moved SIPRI closer to the national security community by collaborating with Swedish institutions. Traditionally, SIPRI has had something of a Berührungsangst in relation to Swedish foreign and security policy, corresponding to its founders' ambition to identify the Institute as a contribution to international efforts for peace and security rather than as a narrow national institution, of which there are 10 to the dozen in the world.

Now, after 40 years of existence, SIPRI is secure in its place as a pre-eminent think tank in Europe and can, without losing its sense of identity, interact with the policy, academic and media communities in its immediate environment. Hopefully, these contacts will turn out to be mutually rewarding.

Even if it can be rightly said that the history of SIPRI is the history of its directors, this is a truth with many qualifications. As regards the Institute's published works, the standards set by the researchers and editors have from the outset until today been impeccable as regards both creativity and treatment of source materials. The history of SIPRI should be judged in the light of this magnificent output. The honours for that work must go to the staff who through all the years have been devoted to the ideals of SIPRI-innovation, truth and quality.

Ambassador Rolf Ekéus is Chairman of the SIPRI Governing Board and OSCE High Commissioner for National Minorities. He was formerly Director of the United Nations Special Commission on Iraq