In making the case for the supply of S-300 missiles to Syria, Russia’s highly experienced foreign minister, Sergei Lavrov, tried to make the point that his government was only selling Damascus “a purely defensive system.” The S-300, he said, as was clear from its name, was for purposes of “air defense.”In other words, he was suggesting that there were weapons systems, like air defense missiles, that were inherently defensive by their nature.The writer is president of the Jerusalem Center for Public Affairs. He served as ambassador to the UN and as foreign policy adviser to the prime minister.Ironically, by making this argument, Lavrov was undermining one of the main pillars of Moscow’s case against other defensive systems which it has opposed vociferously in the past. If defensive weapons systems should not be opposed because, by definition, they have no offensive applications, then why not accept US missile defense deployments in Eastern Europe or in other countries ringing Asia? For while Russia has been stressing that its air defense systems are not offensive in character, it has been strenuously opposing missile defenses for many years, refusing to see them as defensive weapons alone. Since president Ronald Reagan first proposed the US anti-missile system known as the Strategic Defense Initiative (SDI) – also called the “Star Wars” program – in 1983, Russian strategists argued to their American counterparts that missile defenses are inherently destabilizing. During the Cold War, stability was based on the maintenance of deterrence and the credibility of each superpower’s retaliatory strike capability. The argument against missile defenses back then was that a robust SDI-type system could neutralize the weakened retaliatory capacity of the side that was hit first.This strong opposition to missile defenses was maintained by Moscow after the disintegration of the Soviet Union. To some extent it was intensified as the Soviet missiles forces were degraded and even cut by arms control agreements like START. In 2007, for example, when the Bush administration proposed installing missile defense installations in Poland and the Czech Republic, the chief of the Russian General Staff declared that Moscow would withdraw from arms control agreements with the West in retaliation.In that same year, President Vladimir Putin even compared the deployment of Western anti-missile systems to the Cuban Missile Crisis in 1962.Russian generals in 2007 spoke about targeting these missile defense systems if they were ordered to do so by the Russian leadership. More recently, the US defense correspondent Bill Gertz reported on Russian military exercises simulating an attack on US sea-based missile defenses deployed on an Aegis cruiser near Japan.In a speech in late December 2009, Putin laid out the logic behind the Russian opposition to missile defenses: “By building such an umbrella over themselves our [US} partners could feel themselves fully secure and will do whatever they want which upsets the balance.”In short, according to the Russians’ strategic doctrine, missile defenses were completely destabilizing.It would take extraordinary political acrobatics to explain why missile defenses in Eastern Europe endanger stability, yet robust air defenses based on the S-300 in Syria somehow contribute to stability.What ultimately gives a weapons system an offensive or defensive character is the strategic context in which it is placed. In 1970, for example, Moscow deployed SA-2 air defense systems in Egypt and then decided to move them up to the Suez Canal, in violation of the US-Soviet Standstill Agreement at the time. By providing the Egyptian Army with an air defense umbrella over the Suez Canal, and in so doing protecting it from the Israel Air Force, Moscow made it possible for the Egyptians to cross the canal three years later and launch the Yom Kippur War. Air defenses were not just for defensive purposes but rather made possible offensive ground operations.In the Syrian case today, Israel is not likely concerned with a surprise attack by the Syrian army like in 1973, given the state of Syria’s ground forces after two years of fighting against rebel troops. What is changing in Israel’s north is the buildup of Hezbollah, backed by a growing Iranian military presence on the ground that has become engaged in combat operations against President Bashar Assad’s opponents.The most immediate problem is Syria’s willingness to deliver advanced weaponry to Hezbollah that can upset key aspects of the strategic balance.Besides the transfer of chemical weapons, Israel has been concerned with Syria providing Hezbollah with long-range anti-ship cruise missiles, like the supersonic Russian Yakhont that can strike targets 300 kilometers into the Mediterranean. Last year, the director of the US Defense Intelligence Agency described the proliferation of such missiles as a concern to the US Navy as well.Israel has also focused on the supply to Hezbollah of surface- to-surface missiles armed with particularly heavy warheads for striking Israeli cities.The payload of the Fateh 110 is 30 times the payload of the Grad rockets used by Hezbollah in 2006.Finally, Israel is monitoring whether Syria is equipping Hezbollah with long-range airdefense missiles like the SA-17.Using Putin’s own logic, supply of the S-300 by Moscow will create an air defense umbrella over Syria which will provide Assad and his generals in Damascus with the security to make these kinds of weapons transfers to Hezbollah and to “do whatever they want which upsets the balance.”This is a development which Israeli officials have clearly stated they must prevent.The next time US officials sit across from Russian negotiators over the deployment of Western missile defense systems, and the Russians charge that missile defenses are destabilizing, Washington should be prepared with all the statements that came out of Moscow insisting that the S- 300 air defense system in Syria is purely defensive and hence threatens no one. President Putin will not accept the application of Lavrov’s statements about the S-300 to the US missile defense deployments, but in taking that position he will be going into important negotiations for Russia with a much weaker hand than he had before.