By mid-2002, the balance began to tip in Iran's favor with the escalation of the Iraqi-US confrontation. The Iranian leadership accurately judged the seriousness of this looming confrontation. Thus, while the Bush administration was engaged in plotting the removal of the Iraqi regime, the Iranian leadership was busy planning how Tehran could strategically gain from any US adventure in Iraq.
Second, in August 2002 Iran's supreme guide Ali Khamenei ordered the formation of a special committee on Iraq to monitor the development of the crisis, formulate Iranian strategy and mobilize the state's resources to promote Iranian interests in post-Baath Iraq. The committee consisted of representatives from defense, intelligence, political, diplomatic, and religious institutions.
The intelligence arm of the Iranian Revolutionary Guards, responsible for promoting "external jihad," was in charge of most, if not all, Iranian activities related to Iraq, including sponsorship and control of the pro-Iran Shiite opposition groups and direct and crucial control of these groups' intelligence and armed wings, as well as militias. Thus, at the time of the US-led invasion of Iraq, Iranian institutions were well placed to advance Tehran's strategic objectives.
Among the chief aims of these institutions were: first, to prevent an American success in Iraq that might undermine the stability and security of Iran, as well as threaten the survival of the Islamic regime at a later stage; second, to establish sustainable Iranian influence in the new Iraq that could serve Iran's long-term strategic regional interests; and third, to prevent the emergence of a strong Iraq that could balance or contain Iran. The Iranian formula was simple: A failed US plus a weak and fragmented Iraq equalled a strong and influential Iran.
http://www.dailystar.com.lb/article.asp?edition_id=10&categ_id=5&article_id=74736