(St. Petersburg)  --  Russian President Vladimir Putin's comment that John Kerry lied to Congress about Syria is raising tensions as the G-20 economic summit begins in St. Petersburg.  Putin said yesterday that the U.S. Secretary of State knowingly lied when he stated that al-Qaeda plays no significant role in the Syrian conflict.  The Russian leader called Kerry's assertion "sad." Putin also claimed, quote, "he is lying and knows he is lying."  President Obama is taking part in the G-20 meetings in Russia today amid mounting pressure from world leaders not to launch military strikes on Syria.