Over the past few days, nuclear proliferation and the legality of nuclear weapons have garnered a lot of attention.  With the revelation that Iran has a secret nuclear facility close to completion, many leaders are making demands that Iran open the facility for inspection and confirm that it is not for military purposes.

But all this made me wonder: how is Iran’s nuclear weapons program actually illegal under international law?  The law of nuclear proliferation is a confusing field without many clear answers.  Just for the sake of argument, however, let’s assume that the International Court of Justice’s advisory opinion in Legality of the Threat or Use of Nuclear Weapons represents the current state of relevant international law.

First, it’s important to remember that the decision found no particular prohibition (or authorization) in international law against (or for) the use or threat of nuclear weapons.  Therefore, ignoring the Nuclear Non-Proliferation Treaty (NPT), the mere development of nuclear weapons would not be against international law.  Moreover, even threats to use nuclear weapons would not always be illegal.  A mere statement from a country like, “If you attack uswith a nuclear weapon, we’ll attack you,” for example, would probably be ok.  For a while, it seemed like that’s all Iran was saying.  For instance, in 2001, Iran’s President said:

Regarding atomic energy, we need it now… Our nation has always been threatened from outside. The least we can do to face this danger is to let our enemies know that we can defend ourselves. Therefore, every step you take here is in defense of your country and your evolution. With this in mind, you should work hard and at great speed.

That statement seems purely defensive.  Unfortunately, the rhetoric seems to have stepped up.  Here’s one recent statement about the [formerly] secret Iranian nuclear facility:

“God willing, this plant will be put into operation soon, and will blind the eyes of the enemies,” Fars [news agency] reported Saturday, quoting a senior Iranian official.

The senior official, Hojjatoleslam Mohammad Mohammadi Golpayegani, heads the office of the country’s supreme leader, Ayatollah Ali Khamenei.

“Blinding the eyes of the enemies” would seem to go beyond the requirements of proportionality and necessity, making that threat illegal. 

Most importantly, Iran ratified the NPT in 1970.  That treaty imposes separate obligations recognized by the ICJ in Nuclear  Weapons, many of which Iran would seem to have broken if they’re building nuclear weapons.  Some of the highlights include:

• Article II, which states that non-nuclear signatories (like Iran) agree “not to manufacture or otherwise acquire nuclear weapons or other nuclear explosive devices; and not to seek or receive any assistance in the manufacture of nuclear weapons or other nuclear explosive devices”;
• Article III, which requires states to permit inspections by the International Atomic Energy Agency; and
• Article VI, which requires all states to engage in good faith negotiations towards nuclear disarmament.

-Michael