Almost immediately after the 2003 invasion, Iraq became a battleground between the U.S. and Iran, as the latter sent troops, money, and arms to foment and support an insurgency. The war on Islamic State, along with the Obama administration’s effort to align itself with the Islamic Republic, led to a temporary truce, but also gave Tehran-backed militias a great deal of power. Iran has also established a major conduit of supplies through Iraq to support its efforts in Syria. Meanwhile, it is hard to say if the recent elections have brought a government to Baghdad that will be pro-American or pro-Iranian. Eldad Shavit and Raz Zimmt comment how these developments might affect Israel:
Although statements by the U.S. administration have addressed Iran’s overall activity in the region, they appear to emphasize the potential for confrontation in Iraq. First and foremost, this [emphasis] stems from the U.S. perception of this arena as posing the greatest danger, in light of the extensive presence of U.S. military and civilian personnel operating throughout the country, and in light of past experience, which saw many American soldiers attacked by Shiite militias under Iranian supervision. The American media have reported that U.S. intelligence possesses information indicating that the Shiite militias and other elements under Iranian auspices intend to carry out attacks against American targets and interests. . . .
In light of Iran’s intensifying confrontation with the United States and its mounting economic crisis, Tehran finds it essential to maintain its influence in Iraq, particularly in the event of a future clash with the United States. The Iranian leadership has striven to send a message of deterrence to the United States regarding the implications of a military clash. . . .
A recently published report also indicates that Iran transferred ballistic missiles to the Shiite militias it supports in Iraq. Although Iran has denied this report, it might indeed attempt to transfer advanced military equipment to the Shiite militias in order to improve their capabilities in the event of a military confrontation between Iran and the United States and/or Israel, or a confrontation between [the militias] and the central government in Baghdad.
From Israel’s perspective, after years when the Iraqi arena received little attention from Israeli decision makers, Prime Minister Benjamin Netanyahu and Defense Minister Avigdor Liberman have mentioned the possibility of Israel’s taking action against Iranian targets in Iraq. In this context, and particularly in light of the possibility that Iraq could become an arena of greater conflict between the United States and Iran, it is critical that there be full coordination between Israel and the United States. This is of particular importance due to [the American estimation of] stability in Iraq as a major element of the the campaign against Islamic State, which, though declared a success, is not yet complete.
Read more on Institute for National Security Studies: http://www.inss.org.il/publication/iraq-conflict-arena-united-states-iran/