Russian President Putin pays a visit to Iran bearing gifts

Russian President Vladimir Putin paid a visit to Iran's supreme leader in Tehran on Monday and brought along two coveted deals.

Before leaving Moscow, Putin lifted a ban on uranium exports to Iran. The move is linked to Russia's plan to import enriched uranium from Iran, according to Russian state-owned media site RT. The nuclear deal signed between Iran and world powers in July requires Iran to dilute or ship 98% of its enriched uranium, and it does not have the capacity to dilute it.

Putin also presented Ayatollah Ali Khamenei with a copy of the Quran, Islam's holy book, according to the supreme leader's website.

Iranian media on Monday reported that Russia also began delivering an advanced S-300 air-defense system that had been on hold for years.

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Iran’s ambassador to Moscow, Mehdi Sanaei, said the missile-delivery process began under a new contract between Tehran and Moscow, according to Iranian state-owned media Tasnim. In April, Putin lifted a ban on selling five S-300 missile systems to Iran, according to a deal reached in 2007 that was suspended in 2010, as world powers sought to pressure Iran to negotiate limits to its nuclear program.

Putin also addressed a natural gas export summit in Tehran — both Russia and Iran are large gas exporters. And he met Iranian President Hassan Rouhani. The two were shown shaking hands at the summit in Iranian and Russian government-released photos.

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The deals anticipate that world powers will soon lift economic sanctions against Iran in exchange for steps it has promised to take for at least a decade under the nuclear agreement to prevent it from developing a nuclear weapon. Iran has begun but has yet to complete all measures necessary to begin implementation of the deal.

The visit comes as Russia and Iran are increasingly cooperating in multiple arenas, notably their joint efforts to preserve the regime of Syria's President Bashar Assad in his civil war by providing military support and diplomatic pressure on his behalf.

Russian airstrikes helped forces loyal to the Syrian government take control of two strategic towns in western Syria from Islamic State militants, Reuters reported Monday. The towns are east of the north-south highway that connects Syria's major cities, and they are close to the ancient city of Palmyra, a UNESCO world heritage site. The militants have been blowing up ancient structures and stealing smaller artifacts to sell on the black market. Russian ground troops joined the fighting for the first time, according to a report in the Kuwaiti daily al-Rai, The Jerusalem Post reported.

Russian military forces deployed T-90 tanks and air support in battle with rebel forces in Idlib and Latakia, according to the report, which has not been substantiated by other sources, according to the Post.

Russia and Iran have also been participating in talks with the United States, Arab and European countries seeking to end the four-year Syrian civil war, which has killed more than 250,000 people and displaced about half the nation's pre-war population of 22 million people, sending millions to neighboring Turkey, Lebanon and Jordan and hundreds of thousands to Europe.

The U.S., Turkish and Saudi Arabian governments want Assad to step aside as part of a plan to end the war, but Russia and Iran have remained strong supporters of Assad.