As American forces continue to mount airstrikes on Islamic State positions around the key Mosul dam in support of Kurdish forces, it appears that Iran is prepared to increase its military support for Iraq’s Shia in the south and east.

An unconfirmed report in Iraqi News indicates that Iranian Revolutionary Guards forces are preparing to insert heavy armor into Iraq.

According to an informed source, tanks and armored vehicles belonging to the Iranian Revolutionary Guards are mobilizing to enter the Khanaqin district with the aim of the concentration in areas with Shiite majority north of the capital Baghdad and hit the insurgent of the Islamic State in Iraq and the Levant.

The source said that a convoy of tanks and armored vehicles moved through Serpil Zahab, a way to enter Iraq through the border crossing, which links between the two countries from Khanaqin district.

The source added that the Iranian forces will go to the areas which witnessed fighting between the Kurdish Peshmerga forces and militants of ISIL such as Jalawla, which had fallen to the insurgents recently. It is believed that the Iranians want to flush out the militants and deliver these areas to the Peshmerga fighters.

As if American negotiations with Iran over their nuclear program were not complicated enough by Washington’s reliance on an increasingly unhelpful and expansionist Russia to act as a mediator, American dependence on Tehran to serve as stabilizing force in Iraq is probably going to gum up the works in Vienna even further.

Reuters previously reported that, while Iran officially denies that its forces are engaging in combat operations inside Iraq, the recent deaths of Iranian fighters inside the neighboring country “shows that Iran has committed boots on the ground to defend Iraqi territory.”

“Regional experts believe the Revolutionary Guards have increased the supply of weapons and funds to proxy militant groups inside Iraq in recent weeks,” Reuters further reported.

American cooperation with Iran in Iraq is not merely limited to military operations. Last week, Iran withdrew its support for embattled former Prime Minister Nouri al-Maliki and backed his chosen successor, Haider al-Abadi.

Abadi himself, long exiled in Britain, is seen as a far less polarising, sectarian figure than Maliki, who is also from the Shi’ite Islamic Dawa party. Abadi appears to have the blessing of Iraq’s powerful Shi’ite clergy, a major force since U.S. troops toppled Sunni dictator Saddam Hussein in 2003.

If and when the ISIS threat is diminished in Iraq, Iran will have established a foothold in Iraq which the West will find difficult to dislodge. When the fighting subsides, maybe Tehran will show they have learned from America’s mistakes and will negotiate a long-term status of forces agreement to ensure the gains they have made are not so easily lost.