Why did Russia allow Israel to attack Iran?

On 9th May, on Wednesday, Israeli Prime Minister Benjamin Netanyahu visited Russia on the sidelines of Russia's Victory Day against Germany in World War II. Netanyahu was the only head of the world, who ran in response to the invitation of Russian President Vladimir Putin on the occasion of this year in Moscow. He enjoyed the program of the annual military exercise organized on the occasion of one of the most important day in Russia's history, with Putin on his shoulders.

Before the start of the journey, Netanyahu told reporters that the need for the continuation of the Israeli Defense Force's military compromise with the Russian army in what is happening now in Syria must be reaffirmed. Netanyahu definitely received an optimistic response in his discussion with Putin. Because he said in a statement given to journalists before leaving Russia, there is no basis to believe that Russia will obstruct Israeli military measures in Syria.

Netanyahu's statement that it was not mere formalities, its evidence was found that only a few hours later On that day, at night, Israel fired at least 60 missiles in Syria's ground from its air force's 28 F-15 and F-16 war planes. The ground missiles from 10 more grounds, fired from the Golan Plateau. They hit about 50 military installations in Iran, located in Syria. At least 27 people were killed, including eleven Iranian and six Syrian soldiers.
The Israeli invasion of Syria was the biggest attack since the 1973 Arab-Israeli war. Many expected that since Bashar al-Assad's government is the biggest ally in Russia's Syrian civil war, Russia will have a strong response after this attack. But in reality, Russia did nothing like that. Riquidly condemning Russia's Middle East counterpart Mikhail Bogdinov gave a fairly neutral statement, where the newly-launched conflict was referred to as anxious and urged both sides to ease tensions.

Netanyahu's visit, his statement, and lastly, in Russia's role, Business Insider, Jerusalem Post, Hertz, and other newspapers, were suspected in the press, there were Russian green signal behind Israel's attack on Iranian deployments. In addition, journalist and military historian Babak Tangvai cited a source unwilling to disclose the name of the Russian Defense Ministry, Putin asserted that during Netanyahu's visit, Putin assured him that if Russia attacked the establishment of the Revolutionary Guard in Iran, then Russia would not prevent it.