Rare remarks delivered this week by the secretive, high-ranking Iranian commander coordinating the fight within Iraq against the Islamic State have highlighted Iran's role in the military campaign against the terror group — and heightened unease about the authority being exercised by a person US officials accuse of leading a covert war against its interests.

Maj. Gen. Qassem Suleimani, chief of the Quds Force, Iran's elite special-ops intelligence outfit, made an uncharacteristically high-profile entrance to the conflict in Iraq last summer after the Islamic State seized vast stretches of the country and declared a dubious "caliphate." With Iraq's army in disarray, Shia militias under his control are now at the forefront of the ground battle being waged against the militants, and Iran's semi-official news agency Fars has promoted his assertion that the extremist group is weakened and approaching demise.

"Given the heavy defeats that the ISIL and other terrorist groups in Iraq and Syria have sustained, we are sure that these groups are nearing the end of their life," Suleimani declared at a ceremony commemorating the Iranian Revolution on Wednesday, referring to an alternative name for the Islamic State, which is also known as ISIS and by its Arabic acronym Daesh.

The Islamic State has recoiled in the face of a US-led bombing campaign coupled with Kurdish and Iraqi offensives, but still controls large portions of Iraq and Syria.

Suleimani's visibility at the ceremony was the latest in a string of notable public appearances by the general, who is widely described as a shadowy and mysterious figure. Since last summer, Suleimani has been photographed meeting with Kurdish peshmerga fighters in Irbil and alongside high-ranking members of Iraqi Shia militias. Many of the pictures have been widely shared on social media.

Qassem Suleimani with a group of peshmerga fighters in Kurdistan Photograph— ???????/#???...??_?????... (@Forat1352)December 8, 2014

The extent of Iran's troop presence in Iraq is unclear, but the deaths of several high-level military officials have been reported in Iran. Earlier this week, it was reported that Reza Hosseini Moghadem, a commander in Iran's Islamic Revolutionary Guards Corps, was killed on February 7 during fighting with the Islamic State in Samarra. In December, the Pentagon reported that Iran's air force had launched raids in Iraq's eastern Diyala province, but denied that the two countries were coordinating against a common enemy.

The US has reason to be wary of Suleimani. The Quds Force is the international wing of the Revolutionary Guards, responsible for clandestine foreign intelligence gathering and security actions abroad.

For decades, the general has helped foster Iraq's Shia militias, notably the Badr Brigade, which was first established in Iran. After the US invasion of Iraq in 2003, Iran-backed militias waged deadly and long-running battles with American troops. US officials believe the Quds Force itself was directly responsible for supplying the militias with advanced explosive devices that could pierce the armor of US vehicles, claiming the lives hundreds of American soldiers during the occupation.

Suleimani is also suspected of helping to plan prominent attacks in several countries. In 2011, an Iranian agent was caught allegedly attempting to hire a Mexican cartel to assassinate Saudi Arabia's ambassador to Washington, DC. A contact at the purported cartel was in fact an American DEA agent, and the bizarre plot to blow up the ambassador at a restaurant near the White House was foiled.

This history of international subterfuge and support of anti-American militias has raised uncertainty about the strategic alignment of a post-Islamic State Iraq — one in which Iran would likely enjoy even greater influence than before.

Ariane Tabatabai, an associate at Harvard University's International Security Program, noted that Suleimani's public relations campaign, which coincided with the capture of Mosul by the Islamic State in June, has also sought to assuage the more immediate concerns of Iranians, many of whom saw the group as a mortal threat to Iran.

"Essentially, it is for a domestic audience," she told VICE News. "Over the summer, you could hear people saying ISIS is at the gates of Tehran."

Iran and Iraq fought a brutal eight-year war during the 1980s, a conflict that lingers in the minds of many in the Islamic republic. Most Iranians are Shia Muslims, a group brutalized by the radical Sunni militants of the Islamic State, who consider them infidels. Iran, meanwhile, has played up its part in the defense of holy Shia cities like Najaf and Karbala in Iraq.

Though Iran's intervention in a neighboring conflict addresses real security threats, it also serves to portray it as an indispensable (if unconventional) ally for the West in the Middle East.

"The campaign without a doubt tells the US that you need us," Hossein Askari, professor of international affairs at George Washington University, told VICE News. "Iran obviously has a lot of boots on the ground and it can send more, unlike the US, where recent wars have made them more unpopular."

That stance, he said, serves Iran during ongoing negotiations to determine the fate of its nuclear program. Western sanctions over the program, coupled with plummeting oil prices, have sent the Iranian economy into free fall, and Askari believes relatively moderate officials within the Iranian government are keen to resolve the impasse.

"When [Iranian President Hassan] Rouhani was running for election, he told the people he would get rid of sanctions and deliver economic prosperity," he said. "The Iranians want a deal, they want the sanctions lifted."

According to Askari, while Iranian citizens are sometimes wary of much-needed resources being sent to support the Lebanese militia Hezbollah, embattled Syrian President Bashar al-Assad, or Houthi rebels in Yemen, they are less likely to criticize involvement in Iraq, where they see more at stake.

In Wednesday's speech, Suleimani said that in contrast to Iran's gains in Iraq, US interventions, along with "the terrorist acts of the ISIL are doomed to failure because they are not in a quest for truth."

"We have all witnessed in Syria that the measures they adopted did not produce any fruit [for them]," he told the crowd.

Though rarely acknowledged, American officials have conceded that the two countries' interests overlap in Iraq — even as the US relies heavily on support from its traditional Arab allies in the region. Foremost among them is Saudi Arabia, which is seen as Tehran's principal foe in a tussle over influence.

"I think it's self-evident that if Iran is taking on ISIL in some particular place, and it's confined to taking on ISIL and it has an impact, its net effect is positive," Secretary of State Kerry told reporters in December. "But that's not something we're coordinating."

Iran's aims are broader than defeating the Islamic State, according to Suleimani.

"Today we see signs of the Islamic revolution being exported throughout the region, from Bahrain to Iraq and from Syria to Yemen and North Africa," he said.