Twenty years ago, the fall of the Berlin Wall promised great hope that Cold War divides would vanish, ushering in a new era of peace and security based on what former Soviet leader Mikhail Gorbachev called a “common European home” and former U.S. President George H.W. Bush called a “Europe whole and free.”

Over the intervening years this moment never arrived, but neither has the hope died. This month, we will initiate an international commission to build the intellectual framework for an inclusive transatlantic security system for the 21st century — the Euro-Atlantic Security Initiative — devised by the Carnegie Endowment for International Peace.

The stunning events of 1989 remind us of how much remains undone and how important it is to bring fresh thinking to the core questions: What does European security mean in our day? What are the key challenges to it? How can existing structures, principles and institutions be reconciled and strengthened to meet these challenges? Nested within these fundamental questions are the many common perils facing all of our countries — including the spread of weapons of mass destruction to the instability created by the unresolved conflicts that dot the continent, the threat of terrorism, the uncertainties of climate change and the frictions surrounding the stable supply of energy.

These are not questions for tomorrow. Unaddressed they virtually guarantee that the core tension between Russia and the West will remain with a continuous risk of worsening. The uncertainties surrounding Europe’s unfinished security agenda — uncertainties sharply focused by the events of the last two years — not only leave important parts of Europe insecure and capable of generating trouble for all, but they seriously impede progress on the day’s most urgent problems.

There will be less success in controlling, let alone eliminating nuclear weapons, if either Russia or key NATO states are on edge over security arrangements in this crucial region. Progress on climate change will be slow unless those countries most important to a solution have a broad stake in cooperation. Cooperation in dealing with the turbulent areas of the world has slim prospects if cooperation does not prevail in the case of Europe’s own trouble spots. And the list goes on.

To address these questions afresh and to find substantial common ground, the commission will look comprehensively at the full range of security challenges facing our countries, assess the capacity of existing institutions to cope with them and recommend steps by which the great swath of nations from the Atlantic to the Urals could be transformed into a genuinely common security space. The aim must be a community of nations where all generally agree on the security threats that they confront, believe cooperation is crucial in coping with them and work seriously to overcome the obstacles to it.

We know this will not be easy. The security challenges facing our countries are many, diverse and difficult, and our differences in defining and addressing them are considerable. The accumulation of past disappointments, enduring suspicions and damaging misconceptions weighs heavily. Thinking small, however, will get us nowhere. Hence, without losing sight of Europe’s realities, we intend to approach the task by conceiving of security broadly: a domain encompassing not only the traditional threats to national peace of mind, but new sources of unease, including energy and environmental insecurity. Determining how these new and old threats relate to one another stands as a key challenge for the commission.

We will start by addressing the hard unanswered questions of the moment: What is the path to greater security for those countries standing outside the continent’s existing security institutions? How can tension-filled relationships, such as that between Russia and Georgia, be eased and set on a more constructive course? What could be the elements of a more comprehensive European security architecture? And how can Europe’s existing institutional framework including NATO and the Organization for Security and Cooperation in Europe as well as more recently created organizations, such as the Collective Security Treaty Organization, be enhanced to deal more effectively with the immediate threats of nuclear proliferation, terrorism, the conflict over energy resources, the flow of narcotics, dueling pipeline projects and the tattered state of conventional arms control?

We do not pretend to be able to answer all of these questions, so we are all the more eager to cooperate with others who intend to address various elements of this formidable agenda. Nor do we start from the assumption that an improved security environment in Europe can or should be predicated on a major recasting of institutions, including the European Union and NATO. But we are convinced that we will all benefit if our nations can find ways to give traditional forms of security cooperation the added underpinning of a vibrant common economic space, across which goods and services — including oil and gas, capital, people and ideas — can freely flow.

Wolfgang Ischinger was German deputy foreign minister from 1988 to 2001 and ambassador to the United States from 2001 to 2006. Igor Ivanov was foreign minister from 1998 to 2004. Sam Nunn was chairman of the Senate Armed Services Committee from 1986 to 1995.