MOSCOW – It is arguably the world's most widely talked about weapons, and one of the most elusive. The question of whether or not Russia has supplied the S-300 air defense missile systems to Syria has drawn a flow of opaque statements by senior officials in Russia, the United States, Israel and Western Europe. President Vladimir Putin finally offered an answer Tuesday, saying Russia signed a deal to deliver the missiles to Syria a few years ago, but hasn't fulfilled it yet.
Here is a glance at the weapon and the controversy surrounding it:
The S-300 has a range of up to 200 kilometers (125 miles) and the capability to track down and strike multiple targets simultaneously with deadly precision. Russian officials say it's also capable of shooting down warheads of short- and medium-range ballistic missiles.
Russian officials have boasted that the S-300 is superior to the U.S. Patriot missile system. Putin on Tuesday described it as "perhaps the best such weapon in the world."
Along with the Russian military, the S-300 is in service with several other ex-Soviet nations and former Soviet bloc countries. Other operators include China, Venezuela and NATO member Greece.
However, the S-300 has never been used in combat, unlike the Patriot system which was used in the 1991 Gulf war and the 2003 war in Iraq.
Israel has warned that the S-300 shipments to Syria would cross a red line and threatened to attack the missile batteries if they are delivered. The S-300s would limit Israel's freedom to act even in its own airspace and pose a strong challenge to any possible air attack.
Israel also fears that advanced Russian weapons could fall into the hands of Hezbollah, a key Syrian ally in neighboring Lebanon.
The S-300 is not an instant game-changer: Russian military analysts say missile crews would need a year of training.
SYRIAN DEAL CONTROVERSY:
The talk of a sale of the S-300s to Damascus has been around for several years. Last month, Israeli officials asked Russia to cancel what they said was an imminent sale. Israeli Prime Minister Benjamin Netanyahu rushed to visit Putin to discuss the issue, but neither leader has spoken publicly about the issue until Putin's statement on Tuesday.
Last week, Russia's Deputy Foreign Minister Sergei Ryabkov confirmed for the first time that Moscow has a contract to provide S-300s to Syria, but wouldn't say whether any had been shipped.
On Thursday, a Lebanese TV station said it had an interview in which Syrian President Bashar Assad said his government had received the first batch of S-300s. In the actual interview broadcast later, Assad made no specific reference to the S-300.
Israel's Defense Minister Moshe Yaalon said Monday that according to "Russian talk," the S-300s have not been delivered.
Finally, Putin said definitively that Russia hasn't fulfilled the deal.
Russia has shrugged off Western and Israeli criticism of its arms sales to Assad's regime, but it has clearly abided by certain limits and refrained from providing the most potent arms systems. It has refused persistent Syrian demands to deliver short-range Iskander missiles.
At the same time, the Kremlin's refusal to cancel the S-300 deal strengthens its hand in arguments with the West over Syria. If the United States or its NATO allies move to provide weapons to Syrian rebels despite strong Russian criticism, Moscow may respond by shipping S-300s.
Russia similarly played the S-300 card in the Iranian nuclear standoff, signing a contract for their delivery but eventually shelving the deal.