DUSHANBE, October 16, Asia-Plus – Russian President Vladimir Putin is in Iran for a historic visit, the first visit by a Kremlin leader since Stalin joined a summit there in World War II.  He is to meet Iranian President Mahmoud Ahmadinejad and the powerful spiritual leader, Ayatollah Ali Khamenei.

Iran''s nuclear program is set to top the agenda, with the BBC''s Jon Leyne in Tehran saying Iran is seeking Russian help fending off new UN sanctions.

The visit went ahead despite Kremlin warnings of an assassination threat.

The alleged plot to kill the Russian president prompted Mr. Putin''s staff to cast doubt on the trip, only for the Russian president to announce that he was not deterred.

The Iranian government played the threat down.

As well as wanting to secure diplomatic help in blocking UN sanctions over its refusal to end its controversial nuclear program, Iran also wants to ensure continued Russian technical assistance.

The government hopes Mr. Putin will confirm that Moscow will complete the Bushehr nuclear reactor being built by Russian engineers.

It is a program that has been dogged by delays, with Moscow claiming Tehran is behind with its payments and Iran suspecting Russia is dragging its feet for political reasons, our correspondent says.

It is not clear quite how much support Mr. Putin is prepared to give Iran in its showdown with the West.

Washington and other Western countries are pressing for a new round of UN sanctions because of Iran''s refusal to end uranium enrichment.

Moscow has until now been blocking those new sanctions, saying it wants to enable the UN''s nuclear watchdog, the IAEA, to work with Iran on clearing up outstanding issues.

Mr. Putin will certainly be calling for more flexibility from the Iranian government over the nuclear issue and no-one should forget the deep legacy of suspicion that exists between Russia and Iran, our correspondent says.

Mr. Putin has called for a peaceful resolution of the dispute, urging the international community to show patience in the matter.

"It is futile to frighten Iran and its people - they are not scared," Mr. Putin said before the visit.

Mr. Putin''s is also attending a summit of leaders of Caspian Sea states which has brought together the sea''s five littoral states - Russia, Iran, Azerbaijan, Kazakhstan and Turkmenistan.

They are expected to make an announcement on a convention determining a new legal status for the resource-rich body of water, according to the Russian foreign ministry.

Mr. Putin traveled to Tehran from Germany where he met Chancellor Angela Merkel for talks somewhat overshadowed by the alleged assassination plot.

Russian media had quoted unnamed security sources as saying suicide bombers and kidnappers were plotting to kill Mr. Putin in Tehran.

Mr. Putin''s spokesman Dmitry Peskov had told the BBC that such reports were "very serious".

But the Russian president dismissed the claims, telling reporters: "Of course I am going to Iran."

"If I listened to what the security services said, I would never leave my home."