Iran's supreme leader Ayatollah Ali Khamenei on Monday warned regional countries of the "high price" they would eventually pay for supporting extremist Sunni Muslim groups fighting Tehran's key ally Syria. Shiite Iran is a staunch supporter of President Bashar al-Assad's regime in its struggle against mostly Sunni rebels backed by Arab nations and Western powers. Khamenei made the comments during a meeting with the visiting Kuwaiti Emir Sheikh Sabah al-Ahmad Al-Sabah whose trip to Tehran has been widely seen as an attempt to warm up the frosty ties between Iran and Sunni-ruled monarchies in the Gulf.