The following is the full text of South Korean President Lee Myung-bak's speech at a plenary session of the Nuclear Security Summit on Tuesday.

Distinguished leaders from around the world, Your excellencies, distinguished delegates,

I would like to extend, on behalf of the Korean government and its people, a most heartfelt welcome to all of you who are here attending the 2012 Seoul Nuclear Security Summit. It is with great pleasure that we host the Seoul Summit.

The maintenance of peace and security for humankind is a solemn duty that we all assume. Yet, as you are all too well aware, the proliferation of nuclear weapons and the threat of nuclear terrorism pose a grave challenge to peace and security. Realizing a world without nuclear weapons and a world free of nuclear terrorist threats is the earnest wish of all peace-loving people.

We have a long, arduous road ahead of us. Nevertheless, we can realize our dream if we, the Leaders here today, bring together our collective political will.

Should nuclear materials fall into the hands of terrorists, humanity will face a most daunting threat and challenge. This is because there is no effective way to deter terrorist groups from using nuclear materials once they have it. Terrorists know neither mercy nor compromise; they will not hesitate for a moment in taking away innocent lives to obtain their goals.

Moreover, there still exist around the world 1,600 tons of highly enriched uranium and 500 tons of plutonium today. This is enough material to manufacture more than 100,000 nuclear weapons. 

We must seek a fundamental solution and the most optimal way to prevent nuclear terrorism is to promptly minimize and eventually eliminate excess nuclear materials which can be used as ingredients for nuclear weapons.

Until then, however, we must securely protect our nuclear materials to ensure that it does not fall into the hands of terrorists or criminals possession and prevent illicit trafficking thereof. The primary responsibility rests with individual countries. 

Yet international cooperation and coordination is imperative since terrorism knows no borders and because the tragedy of a nuclear terrorist attack is in no way limited to the target country itself. That is the very reason why we are gathered here today.

In this regard, the first Nuclear Security Summit held two years ago in Washington D.C. set an important milestone. We have made meaningful progress over the last two years building upon the Washington Communique and the Work Plan.

It is my sincere wish that during this Seoul Summit we can build on that progress and yield more advanced and practical commitments and agreements. In particular, significant advances must be made in eliminating and minimizing the use of nuclear materials including highly enriched uranium and plutonium; enhancing international cooperation which is crucial in detecting, tracking and responding to illicit trafficking of nuclear material; and securing the universality of international norms.

The Fukushima nuclear accident a year ago awakened the world anew to the imperative need to strengthen safety at our nuclear power plants. We need to address nuclear safety and security in a coherent framework which will ensure the peaceful uses of nuclear energy.

We can prevent nuclear terrorism if the world, including all the Leaders here, unite and work together.

In this age there is no place that can be free from nuclear terrorism. We all share the same fate. I believe that it is our joint responsibility to work towards making a community of peace.

We must show resolve. We must make concrete commitments. And we must take action. We also have a responsibility to our children and to future generations: a responsibility to protect their peace, safety and happiness.

The eyes of the world are upon us to do just that at this Seoul Summit. As Chair, I will do my utmost to make sure, with real outcomes, that we all live up to the expectations.

It is in this spirit and with this sense of great determination that I declare this 2012 Seoul Nuclear Security Summit open. (Yonhap News)