Syria is in growing danger of being lost to Iran, and taken over by a pro-democracy movement. Iran considers this a potential military and diplomatic catastrophe. Iran seems determined to maintain the pro-Iran dictatorship in Syria, no matter what the cost to the Syrians. Turkey has been blocking arms shipments heading to Syria.
Iran is growing more concerned with the covert Cyber War effort by Israel. The Stuxnet and Star worms are only two successful attacks that have gone public. There are apparently others that the government is trying to keep quiet.
Iran-US tradeoff? The US seems to have persuaded the Iraqi Kurds not to back Iranian Kurds in exchange for Iran persuading the Iraqi Shia to lay off attacks on American troops.
Iran is becoming a military dictatorship instead of a religious one. The Revolutionary Guard is head of the state oil company, controls nearly half the economy, and recruits for a willingness to kill fellow Iranians. Strategy Page