The good news for Israel is that its outgoing Prime Minister Ehud Olmert has won assurances from Russia that it isn't going to sell advanced anti-aircraft and anti-missile systems to Iran.

The bad news is that Russia already has sold a lot of other dangerous things to Iran, and its position on the S-300 could change too. Also the assurance in question didn't actually mention the S-300 system that so alarms the Israelis. It didn't mention the Iskander-E missiles that Syria wants from the Kremlin either, for that matter.

Iran already has taken delivery of a series of Tor-M1 anti-aircraft and anti-missile defense systems from Russia. But the Tor-M1 could be regarded as roughly equivalent to the U.S. Patriot anti-ballistic missile interceptor in its tactical role: It is designed to shoot down targets flying at very low, low or medium altitude. If the Iranians want to try to shoot down U.S. B-52s or Stealth bombers flying at great altitudes, or Israeli aircraft flying high, they would want a lot of S-300s.

The Russians assured the Israelis years ago that wasn't going to happen. And while Russian-Israeli relations seemed to be good during most of this decade, especially during the five-year premiership of Ariel Sharon in Israel, that remained the case. However, even then, Russia did sell Iran its Tor-M1 systems in a $700 million deal and went ahead with building Iran's nuclear reactor complex at Bushehr.

However, the Russians have been infuriated by what they regarded as reckless Israeli support for the former Soviet republic of Georgia in the Caucasus and its strongly pro-American President Mikheil Saakashvili. Following the Russian army's occupation of one-third of Georgia in a fast and efficient campaign Aug. 8 to Aug. 12, the Russian press has alarmed the Israeli government by dropping hints the Kremlin may sell the S-300 to Iran after all, as well as selling short-range, solid fuel, highly accurate Iskander-E missiles to Syria.

Olmert, who has been forced to step down because of a major corruption probe, flew to Moscow to try to persuade Russian President Dmitry Medvedev and Foreign Minister Sergei Lavrov not to do those things. And on Thursday, the Russian Foreign Ministry announced the S-300s would not be made available to Tehran or other countries "in volatile regions."

"We have repeatedly said that we do not plan to supply those types of weapons to countries located in volatile regions," spokesman Andrei Nesterenko stated, according to a report from the RIA Novosti news agency.

Selling weapons like the S-300 "run(s) contrary to both Russia's foreign policy and its interest in maintaining stability in different regions," Nesterenko continued.

"Any country can decide to purchase some types of Russian weapons, but we made decisions at the top political level," he added.

Israeli officials quickly responded they were pleased with the Russian statement.

However, one Israeli official, speaking on condition of anonymity, told The Jerusalem Post newspaper that Nesterenko's remarks had been vague and that he had not specifically referred to the S-300s. He cautioned that it was too soon "to celebrate," the newspaper said.

The S-300PMU1 -- NATO designation SA-20 Gargoyle -- has a range of more than 100 miles, with the capability of destroying ballistic missiles and operating at both low and high altitudes.

Some analysts have even claimed that the S-300 could have an 80 percent interception rate capability against America's old, slow and in many respects obsolete subsonic Tomahawk cruise missiles.