Russia took advantage of thawing international relations with Iran on Monday to resurrect its delivery of defensive weapon systems to the Middle Eastern nation.
The signing of a decree by President Vladimir Putin means that it can resume a self-imposed ban and offer S-300 anti-missile rocket systems to Iran for the first time since 2010.
Sanctions from the United Nations had originally pressured Russia into stopping deliveries, but the Kremlin's U-turn comes after world leaders came to a preliminary agreement over Iran's nuclear program.
Moscow looks to be offering itself as a trading partner to Iran as the country verges on being welcomed back onto the global stage.
However, the international nuclear talks with Iran are yet to produce a definite accord and no economic sanctions have officially been curbed. The next major deadline for the talks is June 30.
Russia will also supply grain, equipment and construction materials in exchange for crude oil from Iran, according to Reuters, which cited a senior government official.