A delegation from the International Atomic Energy Agency left Iran empty-handed on Wednesday. Security expert Oliver Thränert, of the German Institute for International and Security Affairs in Berlin, explains Tehran's hard line - and says the West should be patient.

DW: The Iranian government has barred inspectors from the International Atomic Energy Agency (IAEA) from its facilities. Why isn't Tehran cooperating with the IAEA?

Oliver Thränert: Iran has pointed out that, in fact, it is cooperating with the IAEA, based on the framework of the safeguards agreement. This agreement only covers nuclear facilities that Iran has reported; an inspection would determine whether any fissile material is being diverted to these facilities. An additional protocol that would give inspectors improved access to these areas has been signed by Iran, but not ratified - and the military facility in Parchin, where inspectors have been trying to gain access for the last two days, is not a declared nuclear facility.

What is behind this quibbling over formal details?

The IAEA and the vast majority of international experts assume Iran is working on a secret nuclear weapons program. The IAEA suspects the Parchin military base may be used for weapons-related testing. There is no hard evidence of a nuclear program, but Iran is party to the Nuclear Non-Proliferation Treaty - and a state that has committed itself to arms controls must do its part do demonstrate that it is complying with the treaty.

However, Iran is pursuing the goal of further developing its nuclear program to the point that, if the situation were to warrant it, it could develop a relatively extensive arsenal of nuclear weapons within a very short time. This, at least, is something that I am convinced of.

Is this a rational goal?

Iran is undoubtedly in a difficult security situation. There are already a number of nuclear powers in the region, and the Iranian government is most certainly considering the warning signs from Libya. Former Libyan leader Moammar Gadhafi abandoned his nuclear weapons program in 2003 - with the result that when revolution broke out last year, he was ousted from power with the help of NATO and eventually killed. On the other hand, it's safe for Iran to assume that its nuclear program will force it to pay the price on the international stage, for example in the form of sanctions.

The effect of sanctions has, so far, been negligible. What options remain to persuade Iran to comply?

First, we must wait to see if the new sanctions have any effect. It seems as if the Iranian leadership has already become nervous. The oil embargo adopted by the European Union, along with other measures, is not due to come into effect until July 1, so it's premature to call for new measures. I think it could still be several years before Iran is able to produce nuclear weapons.

Israel believes Iran could be producing nuclear weapons within the year, and has indirectly threatened a military strike…

I seriously doubt this threat. I think Israel is simply trying to get the West and the international community to further tighten the sanctions and other measures against Iran.

What would such a military attack achieve?

The destruction of key Iranian nuclear facilities, there's no doubt about that. The question is, how extensive would an operation like this need to be? Would Israel go at it alone, or would it need US support? But above all, the question we would have to ask would be whether the time gained by such a strike would be worth the international consequences.

An attack would delay Iran's nuclear program, but Iranian countermeasures could lead to a massive increase in oil prices and the all the consequences for the global economy that would go with it. It could also bring about an unwanted destabilization of the Iranian regime. I think that the global community, and especially US President Barack Obama, are not interested in getting into a military confrontation that could spiral out of control.

Interview: Dennis Stute / cmk
Editor: Chuck Penfold