According to a recent report (July 2011), more US troops are being killed by Iranian weapons (though not Iranians!) than ever before.
Military commanders stationed in Iraq have stated than Iranian made weaponry is now the greatest threat to their soldiers.
This highlights Tehran’s push to gain influence in the post-American Middle East region.
14 men were killed in June, a record high, and 12 of these were killed by Iraqi militias who had Iranian backing, so US forces claim.
However, US forces have never discovered any weapons in transit and are unsure about how they might stop these deliveries crossing the border. The Iranian government denies any involvement and has issued a statement that they have never supplied weaponry to any Shia militias operating in Iraq.
Correspondingly, US influence in Iraq is declining. The Obama administration made it clear that should Iraq so choose, they would be willing to leave a small number of troops in the country after their designated withdrawal date.
At present, it does not appear likely that Baghdad would take them up on such an offer.