Russian President Vladimir Putin said that Moscow had provided some components of the S-300 defense missile system to Syria but frozen further shipments. He said they may be sold elsewhere if Western nations attack Syria without UN Security Council backing. This remark was taken as a veiled threat to deliver the highly advanced S-300s to Iran, which Moscow cancelled some years ago under strong US and Israeli pressure. Putin spoke in an AP interview ahead of the G20 summit opening in St. Petersburg Thursday.