The US President Barack Obama has promised tougher sanctions on Iran after they uncovered an alleged plot to kill the Saudi ambassador to Washington.<br /><br />Already the US has placed sanctions on Iran's major airline Mahan Air, as well as travel and economic bans on five prominent Iranian citizens.<br /><br />But as Iran still continues to enrich their uranium and influence groups like Hezbullah, many are convinced that sanctions have no real impact.<br /><br />Al Jazeera's Kimberly Halkett reports from Washington.
