What's the real value of the Nuclear Non-proliferation Treaty (NPT)?

What’s the real value of the Nuclear Non-proliferation Treaty?

Should every country be a signatory? Should some countries be excluded from sigining it?

Only five states are permitted by the NPT to own nuclear weapons:
The United States (signed 1968)
United Kingdom (1968)
France (1992)
Soviet Union (1968; since replaced by Russia)
The People’s Republic of China (1992).

These were the only states possessing such weapons at that time, and are also the five permanent members of the United Nations Security Council. These 5 Nuclear Weapons States (NWS) agree not to transfer nuclear weapons technology to other states, and the non-NWS state parties agree not to seek to develop nuclear weapons.

http://en.wikipedia.org/wiki/Non-Proliferation_Treaty

In New York City, on May 11, 1995, more than 170 countries decided to extend the Treaty indefinitely and without conditions.

The parties to the treaty are: Afghanistan, Albania, Algeria, Andorra, Angola, Antigua and Barbuda, Argentina, Armenia, Australia, Austria, Azerbaijan, The Bahamas, Bahrain, Bangladesh, Barbados, Belarus, Belgium, Belize, Benin, Bhutan, Bolivia, Bosnia and Herzegovina, Botswana, Brazil, Brunei, Bulgaria, Burkina Faso, Burma, Burundi, Cambodia, Cameroon, Canada, Cape Verde, Central African Republic, Chad, Chile, People’s Republic of China, Colombia, Comoros, Democratic Republic of the Congo, Republic of the Congo, Costa Rica, Côte d’Ivoire, Croatia, Cuba, Cyprus, Czech Republic, Denmark, Djibouti, Dominica, Dominican Republic, East Timor, Ecuador, Egypt, El Salvador, Equatorial Guinea, Eritrea, Estonia, Ethiopia, Fiji, Finland, France, Gabon, The Gambia, Georgia, Germany, Ghana, Greece, Grenada, Guatemala, Guinea, Guinea-Bissau, Guyana, Haiti, Holy See, Honduras, Hungary, Iceland, Indonesia, Iran, Iraq, Ireland, Italy, Jamaica, Japan, Jordan, Kazakhstan, Kenya, Kiribati, North Korea, South Korea, Kuwait, Kyrgyzstan, Laos, Latvia, Lebanon, Lesotho, Liberia, Libya, Liechtenstein, Lithuania, Luxembourg, The Former Yugoslav Republic of Macedonia, Madagascar, Malawi, Malaysia, Maldives, Mali, Malta, Marshall Islands, Mauritania, Mauritius, Mexico, Federated States of Micronesia, Moldova, Monaco, Mongolia, Morocco, Mozambique, Namibia, Nauru, Nepal, Netherlands, New Zealand, Nicaragua, Niger, Nigeria, Norway, Oman, Palau, Panama, Papua New Guinea, Paraguay, Peru, Philippines, Poland, Portugal, Qatar, Romania, Russia, Rwanda, Saint Kitts and Nevis, Saint Lucia, Saint Vincent and the Grenadines, Samoa, San Marino, São Tomé and Príncipe, Saudi Arabia, Senegal, Serbia and Montenegro, Seychelles, Sierra Leone, Singapore, Slovakia, Slovenia, Solomon Islands, Somalia, South Africa, Spain, Sri Lanka, Sudan, Suriname, Swaziland, Sweden, Switzerland, Syria, Tajikistan, Tanzania, Thailand, Togo, Tonga, Trinidad and Tobago, Tunisia, Turkey, Turkmenistan, Tuvalu, Uganda, Ukraine, United Arab Emirates, United Kingdom, United States, Uruguay, Uzbekistan, Vanuatu, Venezuela, Vietnam, Yemen, Zambia, Zimbabwe.

Actually, they gave the required 3 month notice period and withdrew, citing the threat of a neighbour allied to a superpower. Also note that India, Pakistan and Israel are not on that list, but Iran is (hence the careful eye kept on its power stations these days).

What is the Treaty’s value? Well, a nuke hasn’t gone off while it has been in force. Whether it would have done without it is another question.

To pick my own nit, a nuke hasn’t gone off in anger (rather than in test, which is incidentally covered by another Treaty which, surprise surprise, some countries have also refused to sign, and there are even worries that the one who wrote it might tear it up and start testing again.)