If guests to Baghdad knew nothing of Iraqi politics, they could possibly be forgiven for considering that the trim-bearded, green-uniformed man whose larger-than-life photograph is in all places within the Iraqi capital was Iraq’s president.

Alongside the boulevard that tracks the Tigris River and contained in the Inexperienced Zone, the seat of Iraq’s authorities, the likeness of Maj. Gen. Qassim Suleimani towers above roundabouts and stands astride medians. The final particular person to be so glorified was Saddam Hussein, the dictator deposed and killed within the American-led invasion of Iraq that started virtually precisely 20 years in the past.

However Mr. Suleimani was Iranian, not Iraqi.

The commander of the Quds Drive, the exterior arm of Iran’s highly effective Revolutionary Guards Corps, he achieved near-mythic standing in Iraq as an influential pressure who helped bind Iraq and Iran after the invasion. It was thanks largely to Mr. Suleimani, whom the USA assassinated in Iraq in 2020, that Iran got here to increase its affect into virtually each facet of Iraqi safety and politics.

That, in flip, gave Iran outsize affect over the area and past. Tehran’s rise uncovered the unintended penalties of Washington’s technique in Iraq, analysts and former U.S. officers say, and broken the USA’ relationship with its regional allies.

The invasion “was the unique sin,” mentioned Emile Hokayem, a senior fellow for Center East safety on the Worldwide Institute for Strategic Research, a British assume tank. “It helped Iran bolster its place by being a predator in Iraq. It’s the place Iran perfected the usage of violence and militias to acquire its targets. It eroded the U.S.’s picture. It led to fragmentation within the area.”

The U.S. State Division declined to touch upon the impression of the battle in Iraq.

“On Iraq particularly, our focus is on the 20 years forward; much less about wanting backward,” the division mentioned in an e-mail response to questions. “Our partnership at this time has advanced far past safety, to a 360-degree relationship that delivers outcomes for the Iraqi folks.”

All of that was enabled by the political adjustments that the American invasion of Iraq on March 20, 2003, set in movement. Afterward, the 2014 takeover of a big space of northern Iraq by the Islamic State terrorist group prompted Iraq to show to Iran in addition to the USA for assist, cementing Iran’s grip.

As destabilizing because the Iranian involvement has been for a lot of Iraqis, it has been not less than as unsettling for a lot of the remainder of the area.

Iraq and Iran are the 2 largest Center Jap nations with a Shiite Muslim majority, and Shiites emerged from the Iraq battle empowered throughout the area — typically unnerving their historical sectarian rivals, the Sunni Muslims, who dominate most different Arab nations.

Underneath the Iraqi dictatorship, the Sunni minority had fashioned the bottom of Mr. Hussein’s energy; as soon as he was killed, Iran arrange loyal militias inside Iraq. It additionally went on to dismay Saudi Arabia and the opposite Persian Gulf monarchies and Israel by supporting proxies and companions, such because the Houthi militia in Yemen, that introduced violence proper to their doorsteps.

Earlier than 2003, it could have been onerous to think about Saudi Arabia, a pillar of the USA’ Center East coverage for many years and a number one Sunni energy, displaying open anger towards American leaders over their conduct within the area. However the Saudi king on the time did simply that in a January 2006 assembly with the American ambassador to Iraq, telling him that the best way Washington noticed issues moving into Baghdad mirrored “wishful considering,” in keeping with a State Division cable launched by WikiLeaks in 2010.

By the point of that assembly, Iraqis had accepted a brand new Structure and held parliamentary elections that swept Shiite events to energy, and Sunni-Shiite sectarian tensions had escalated.

Saudi King Abdullah instructed the ambassador that earlier than Mr. Hussein’s ouster, his kingdom — Iran’s longtime rival for affect within the Center East — might depend on Iraq as one other Sunni energy maintaining Iran in verify.

Now, he mentioned, Iraq had been handed to Iran like “a present on a golden platter.”

The US, whose army muscle guided its insurance policies, typically with little sensitivity for Iraq’s non secular and political dynamics, in keeping with analysts, was not the nation finest positioned to make lasting inroads in Iraq.

Iran, against this, might construct the bonds created by the Shiite religion it shared with many in Iraq’s inhabitants.

Iranian and Iraqi clerics, together with tens of millions of pilgrims, frequented Shiite shrines in each nations annually and loved a mutual understanding of one another’s tradition. Tribes and households span their almost 1,000-mile-long border. And the daddy of Iran’s 1979 Islamic Revolution, Ayatollah Ruhollah Khomeini, spent 13 years in Iraq’s Shiite pilgrimage metropolis of Najaf, whereas Iraq’s high Shiite cleric, Grand Ayatollah Ali Sistani, was born in a single Iranian holy metropolis and educated in one other.

Nonetheless, that proximity hardly bred friendship, not less than earlier than 2003.

In 1980, when Iraq invaded Iran, the USA and different Western nations quietly supported Iraq within the ensuing battle.

The eight-year battle was so devastating that some analysts say it formed the mentality of a complete technology of Iranian leaders, making them decided to by no means once more enable Iraq to develop robust sufficient to assault them. That would clarify why, beneath Mr. Hussein’s repressive rule, which empowered Iraq’s Sunni minority over its Shiite majority, Iran gave shelter and assist to each Shiites and Kurds within the Iraqi opposition.

When the USA toppled Mr. Hussein, it neutralized Iran’s foremost enemy with out Tehran’s having to raise a finger. Afterward, the Individuals diminished Sunni energy in Iraq by dismantling the nation’s military and purging the Sunni-dominated governing elite.

Iran noticed alternative.

“What they have been in search of and have been in search of isn’t Iranian management,” Ryan Crocker, a former United States ambassador to Iraq, mentioned of Iran. “It’s Iraqi instability.”

After the 2003 invasion, Iranians streamed into Baghdad and Iraq’s Shiite-dominated south: building engineers to rebuild Iraqi cities, political consultants to coach Shiite activists earlier than the Iraqi elections, media professionals to determine Shiite-owned tv channels.

Iranian pilgrims who had been barred within the Saddam Hussein period from visiting Iraq’s Shiite shrines now hurried throughout the border to the Shiite holy cities of Karbala and Najaf, the place Iranian firms invested in acres of motels and eating places for the tens of millions of worshipers, a lot of them Iranian, who go to the shrines annually.

An excellent variety of the Iraqi leaders who emerged after 2003 additionally had ties to Iran. The Shiite and Kurdish opposition politicians who had taken refuge there years earlier than returned to Iraq after the invasion. A few of Iraq’s largest Shiite events had backing and technical assist from Iran, placing politicians from these events in Iran’s debt once they received seats.

The Individuals “one way or the other didn’t make the reference to Iran explicitly and perceive that it’s not the Shiites you might be giving the higher hand to, it’s the Shiites backed by Iran,” Marwan Muasher, who was then Jordan’s international minister, mentioned final week.

Throughout Iraq’s southern border, Saudi Arabia and its gulf allies watched with rising frustration.

Gulf wariness of Iran dated again centuries. Lower than 150 miles of Persian Gulf waters separate Iran from the Arabian Peninsula, a dynamic that has lengthy fueled commerce rivalries and territorial disputes. After the 1979 Islamic Revolution, the Sunni gulf monarchies feared that Iran would export its model of Shiite theocracy throughout a area historically dominated by Sunnis.

Earlier than 2003, the gulf frightened concerning the Iraqi dictator, too. However Western-led sanctions had weakened Iraq, and the Gulf States and the Iraqis shared a typical enemy in Iran.

The toppling of Mr. Hussein unleashed what the gulf noticed as Iran’s harmful energy: Now, Iran was rising its affect over a serious Arab nation with monumental oil reserves on Saudi Arabia’s northern border, simply as proof was rising that Iran was growing a nuclear program.

Lately, no Iraqi prime minister can take workplace with out not less than the tacit approval of each the USA and Iran, an association that usually produces prime ministers torn between Washington and Tehran. Iraqis with connections to Iran maintain posts all through the federal government.

The price of Iranian affect to Iraqi growth and stability has been excessive.

Reduce off from the world financial system by sanctions, Iran has discovered an financial lifeline in Iraq, which buys about not less than $7 billion in Iranian exports a yr whereas promoting solely about $250 million of products in return. The advantageous print on many medicines exhibits that they’re Iranian made, and enormous portions of Iranian building supplies come stacked on truck convoys throughout the border day by day.

Many Iraqi farmers and businesspeople complain that Iran has suffocated Iraqi manufacturing and farming by dumping giant portions of produce and low-cost items in Iraq.

Though Shiites in Iraq’s political elite tolerated Iran’s actions and revered Common Suleimani, resentment of Iran amongst different Iraqis helped set off mass antigovernment demonstrations in 2019 during which protesters demanded an finish to Iran’s interference in Iraqi affairs.

Past Iraq, Iran has used each battle within the area to increase its attain.

It inserted fighters into Syria after the 2011 Arab Spring revolt, aiming to prop up the Syrian president, Bashar al-Assad. It supported the Houthis in Yemen’s civil battle in opposition to a Saudi-led coalition, establishing Iranian affect on the southern Saudi border. And it additional cemented its place in Iraq and Syria by recruiting and coaching Shiite fighters in opposition to the Islamic State.

“Each alternative that there was within the area, the dominoes fell in Iran’s favor,” mentioned Vali Nasr, a professor of worldwide affairs and Center East research at Johns Hopkins College. Exploiting Iraq’s weak point, he added, step by step changed into “a strong international coverage device for Iran on the regional stage.”

Notably worrisome to its Sunni Arab neighbors was Tehran’s consolidation of affect throughout a so-called Shiite Crescent stretching from Iran by means of Iraq and into Syria and Lebanon. Some Sunni governments, chief amongst them Saudi Arabia and the United Arab Emirates, blamed the USA — the nation they’d lengthy relied on to have their backs — for failing to cease Iran from transferring items, weapons and personnel freely throughout the area, analysts say.

Later quarrels within the relationship arose over what the gulf noticed because the U.S. failure to intervene in Syria or to guard the gulf from Iranian-linked assaults on Saudi Arabia and the Emirates.

The State Division mentioned the USA values its relationship with the gulf and is dedicated to “to strengthen cooperation, coordination, and session with our gulf companions in all fields, together with safety, counterterrorism, and financial partnership.”

The gulf stays deeply related to the USA, however because the 2003 invasion it has seemed to broaden and deepen its ties to China and Russia as various companions. When Saudi Arabia agreed to revive diplomatic relations with Iran final week, for instance, it did so in Beijing.

That settlement was the newest signal that Saudi Arabia has determined to strive participating with its adversaries moderately than holding them at arm’s size because the gulf monarchies did for years in Iraq.

Regardless of Iraq and its gulf neighbors’ shared Arab identification, all of them however forfeited the competitors for affect to Iran: Whereas Iran was the primary to determine an embassy in Baghdad after the USA invasion, a Saudi ambassador to Iraq arrived in Baghdad solely final week.

Likewise, the Saudis didn’t open their deep pockets to Iraq till just a few years in the past, once they started a tentative effort to put money into infrastructure.

“The one factor we will do is to offer the Iraqis one other selection that isn’t solely Iran,” mentioned Hesham Alghannam, a Saudi political scientist. “We will’t nook them after which blame them for going with the Iranians.”