Russia may adopt a tougher stance on Iran’s nuclear program, in case Tehran does not withdraw its lawsuit against Russia on missile contract. According to Russian Komersant, the decision has been made by Russia’s authorities.

A government source told the newspaper that this “not nice” situation shows Iran being an “ungrateful” country. “We support them, we have adopted a constructive position in the talks over their nuclear program and this is the way they have responded us,” the source said.

He also said that earlier Moscow has warned Tehran that the filed lawsuit “does not promote the development of relations between the two countries” while these words were “ignored”.

According to the source, Russia will once again try to make its stance “reach the addressee” but if Iran refuses, it [Russia] will have to “make a decision over Iran’s nuclear program on its own.”

The contract on selling S-300 worth $800 million was signed in 2007. Its implementation was periodically postponed because of technical reasons. After refusing to implement the contract, Russia has returned the initially received sum – $167 million.

Iran has filed a lawsuit against Russia at the International Court of Justice for not complying with its commitments on the agreement over delivery of S-300 air defence systems.