In a conference last week, Ali Younesi, President Hassan Rouhani's adviser on Ethnic and Religious Minorities Affairs, was quoted as announcing the birth of a new Iranian empire "whose capital is Baghdad." His provocative words are not completely baseless, as Iraqi forces that are battling the Islamic State of Iraq and al-Sham (ISIS) in Tikrit and that will soon launch an operation on Mosul, are explicitly backed by Iranian forces. Iran's support has overshadowed the U.S.-led anti-ISIS coalition endeavor to eradicate the extremist group from Iraq and Syria, as Iraqi officials praised the Shiite state's economic, strategic and military aid. The sectarian unity with the central Iraqi government and the animosity of Kurds towards deposed former President Saddam Hussein's Arab-Sunni base has gained Iran popularity in the deeply troubled country. In a conference organized by the Irbil-based Middle East Research Institute and the Istanbul-based Al-Sharq Forum last month, a prominent Kurdish journalist thanked Iran for sending its warplanes when ISIS attempted to capture Irbil.

The U.S., which seems to be disappointed by Iran's role in the Tikrit operation and the upcoming Mosul battle, has refrained from providing aerial support and has voiced its concern over the fueling of sectarian conflict, as the Iranian-backed Shiite militias are known for atrocities targeting Sunni civilians. "It is important, as Iraqi Prime Minister Haider al-Abadi himself has indicated, that this operation should not be used as an excuse or as a cover for individuals taking sectarian-motivated retribution," said White House spokesman Josh Earnest. "That would tear at the fabric of the country and weaken the ability of the Iraqis to confront this threat to their country," he added. Earnest also voiced the White House's displeasure with the Iranian involvement, saying, "We have said from the beginning that the United States will not coordinate militarily with the Iranians." Human Rights Watch (HRW) and Amnesty International also warned the Iraqi government about sectarian cleansing in Tikrit.

Capturing Baghdad has historically been a goal of Iran since the city has become a powerful symbol of the struggle between Sunnis and Shiites. In the past, the Ottoman Empire and Iran, two powerful empires of the region, and Sunni and Shiite respectively, have battled over Baghdad several times. During the 20th century, Iran never gave up the aim of seizing Baghdad. As the new world system rarely allows territorial change, Iran has been pursuing sectarian policies to expand its influence towards Baghdad and other Shiite Arabs. The election of former Iraqi Prime Minister Nouri al-Maliki, who was an ardent supporter of Iran, was the first step for Tehran to capture the city economically and culturally, rather than territorially.

Qasem Soleimani, the shadowy commander of the Quds Force, an elite branch of the Iranian Revolutionary Guard, travelled to Iraq to assist and even conduct the military operations against ISIS. His travel and leaked photos on social media have triggered concern among Sunni countries that are considered natural enemies of Iran. Saudi Arabian Foreign Minister Saud al-Faisal said: "The situation in Tikrit is a prime example of what we're worried about. Iran is taking over the country."

Defense Secretary Ashton Carter told a hearing of the Senate Armed Services Committee last week, "I am looking at it [Iranian involvement] with great concern."