An unholy and rocky alliance
Relations between Russia and Iran have not always been at their best. The two countries have differences over control of the Caspian Sea, the Caucusus and Asia Minor.
In the 19th century, the neighbours were engaged in many wars and during the Soviet era, Iran was a US ally and an important member of the Baghdad Pact.
After the Iranian Revolution, the Islamic regime in 1979 withdrew its membership from this Western alliance which at that time was called the Central Treaty Organisation (Cento).
During the second term of Vladimir Putin, relations between the two countries started to thaw. At that time, Putin detached Russia's Middle East policy from the US, a factor which helped to boost Moscow-Tehran ties.
In November 2005, Russia and Iran signed a treaty of cooperation. Russia supplied Iran with $1.4 billion worth of military equipment, including parts to upgrade Iran's military aircraft.
When Putin visited Iran recently, he became the first Kremlin leader to visit Tehran since Joseph Stalin, Winston Churchill and Franklin D Roosevelt attended the famous wartime conference there in 1943.
Putin has issued a veiled warning to the US and other Western forces against an attack on Iran and has suggested that Moscow and Tehran should have a virtual veto on Western plans for pipelines in the oil and gas-rich Caspian Sea region.
In Iran's confrontation with the West over its nuclear programme, Russia has trod a fine line, warning against heavy pressure on Iran and protecting it - for the time being - from a third round of UN sanctions, while also urging Tehran to halt its uranium enrichment programme.
Nuclear plant
Putin's careful stance on completing the Russian-built Bushehr nuclear plant suggested that Russia is seeking to preserve strong ties with Iran without antagonising the West.
Russia has warned that the nuclear plant would not start its operation this autumn as planned because of delays in payment. Iranian officials have angrily denied any payment arrears and have accused the Kremlin of caving in to Western pressure.
The Russian-Iranian relations started deteriorating because Putin suggested that Azerbaijan, a country neighbouring Iran, should be used to deploy the anti-missile shield to counter the one that the US is setting up in the Czech Republic and Poland.
The second reason is related to the slackness of Russia in supplying nuclear fuel for the Bushehr reactor, because Iran has failed to pay its dues, a matter Tehran is rejecting.
Russia and the US are in concert to prohibit Iran from acquiring technical capabilities which may help it to acquire nuclear weapons.
The Russian president has asserted that Russia does not have information regarding Iran's desire to acquire nuclear weapons.
Russia is a great nation and it is striving to return with force to the international arena. It also considers the US presence in the Middle East to be irritating. Moscow is in dire need of improving its relations with the Middle Eastern countries, but will it continue backing Iran, or will crack under pressure?
Russia will not give up easily on Iran because it does not want its Middle East interests to suffer, but Moscow will go on exerting pressure on Tehran to make the Iranian nuclear programme more transparent.
Dr Mohammad Akef Jamal is an Iraqi writer based in Dubai.