Even as we prosecute two wars, we are also confronting perhaps the greatest danger to the American people - the threat of nuclear weapons. I have embraced the vision of John F. Kennedy and Ronald Reagan through a strategy that reverses the spread of these weapons, and seeks a world without them. To reduce our stockpiles and launchers, while ensuring our deterrent, the United States and Russia are completing negotiations on the farthest-reaching arms control treaty in nearly two decades. And at April's Nuclear Security Summit, we will bring forty-four nations together behind a clear goal: securing all vulnerable nuclear materials around the world in four years, so that they never fall into the hands of terrorists.

These diplomatic efforts have also strengthened our hand in dealing with those nations that insist on violating international agreements in pursuit of these weapons. That is why North Korea now faces increased isolation, and stronger sanctions - sanctions that are being vigorously enforced. That is why the international community is more united, and the Islamic Republic of Iran is more isolated. And as Iran's leaders continue to ignore their obligations, there should be no doubt: they, too, will face growing consequences.