A losing battle against proliferation By MICHAEL RICHARDSON

Slowly but surely, the barriers preventing the spread of nuclear technology and materials that can be used to make weapons of mass destruction are being eroded.

The most brazen cases involve North Korea and Iran. The former left the Nuclear Nonproliferation Treaty (NPT), conducted at least two nuclear explosive tests in the past few years and has threatened to carry out more. Iran remains in the NPT but refuses to cooperate fully with the International Atomic Energy Agency (IAEA), the United Nations nuclear watchdog, and is widely suspected of seeking nuclear weapons.