Russia is now moving to ship an air defense missile system to Iran.
The S-300 missile system deal, worth around 800 million US dollars, was originally signed in 2007.
However, the contract was cancelled in 2010 after a UN Security Council resolution passed which banned the supply of conventional weapons to Iran.
Russian Foreign Minister Sergei Lavrov says the preliminary nuclear deal which Iran has agreed to now allows for the original contract to be fulfilled.
"We are convinced that at this stage there is no longer need for such an embargo, specifically for a separate, voluntary Russian embargo. Because of the suspension of the contract, Russia has failed to receive significant funds. We see no need to continue doing that, taking into concern the progress in the Iranian nuclear program settlement."
Iran's defense minister is welcoming the renewal of the contract, saying Russia's decision indicates a political will between the two countries to improve cooperation.
The Israeli government is blasting the Russian move, saying it's a proof that Tehran is benefiting from the nuclear deal by arming itself with advanced weapons.
The US government is also raising concerns.
White House Press Secretary Josh Earnest.
"We're studying the details. And if this sort of arrangement were to move forward, it would raise serious concerns and even could potentially raise sanctions concerns. So we're going to continue to evaluate that moving forward as well."
Moscow's decision to re-establish the missile contract follows on the heels of Iran agreeing to an interim nuclear agreement which should significantly restrict Tehran's ability to produce nuclear weapons in exchange for relief from international sanctions.
