YEKATERINBURG, June 4 (RIA Novosti) – Russian President Vladimir Putin defended his country's sale of S-300 air defense systems to war-torn Syria on Tuesday, but said the contracts for the missiles have not yet been fulfilled.

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The S-300-P surface-to-air missile system

“We do not want to disturb the balance in the region,” said Putin during a joint press conference at the Russia-European Union Summit with European Union President Herman Van Rompuy and European Commission President Jose Manuel Barroso. “The contract was signed several years ago. It has not yet been realized."

Putin praised the capabilities of the Russian-made S-300s, which can engage 12 targets simultaneously at distances of 200 kilometers and heights of up to 27 kilometers.

“The S-300 systems are, really, one of the best air defense systems in the world – probably the best,” he said.

The shipment of S-300s to Syria is a continuing source of friction between Washington and Moscow. US Secretary of State John Kerry said last month that the presence of the weapons in Syria would be “destabilizing” for the region.

Putin also stressed that the deliveries of S-300s to Syria are legal.

“Russian deliveries of weapons to Syria are implemented on the basis of recognized and transparent international contracts,” said Putin. “They do not violate any international position. And they are implemented exclusively, and in their entirety, within the framework of international law.”

Syrian President Bashar Assad suggested last week that the S-300 contracts with Russia would be fulfilled.

“Everything we have agreed with Russia will be implemented, and a part of it has been implemented already,” he said when asked about S-300s, according to Lebanon's Almanar television station.

Updated with new headline and modified first paragraph, changing "Realized" to "Fulfilled" and "delivery" to "sale," respectively.