Nytimes.com | By Farnaz Fassihi, Eric Schmitt and Julian E. Barnes

Iran has made a concerted effort to rein in militias in Iraq and Syria after the United States retaliated with a series of airstrikes for the killing of three U.S. Army reservists this month.

Initially, there were regional concerns that the tit-for-tat violence would lead to an escalation of the Middle East conflict. But since the Feb. 2 U.S. strikes, American officials say, there have been no attacks by Iran-backed militias on American bases in Iraq and only two minor ones in Syria.

Before then, the U.S. military logged at least 170 attacks against American troops in four months, Pentagon officials said.

The relative quiet reflects decisions by both sides and suggests that Iran does have some level of control over the militias.

The Biden administration has made clear that Tehran would be held accountable for miscalculations and operations by proxy forces, but it has avoided any direct attack on Iran. The U.S. response “may be having some effect,” Gen. Kenneth F. McKenzie Jr., a retired head of the Pentagon’s Central Command, said in an interview.

“The question is are the militias attacking or not,” he added, “and at least for now, they are not.”

The lull also marks a sharp turnaround by Iran. Tehran had for months directed its regional proxies in Iraq and Syria to attack American bases in the Middle East as part of a wider battle against Israel, which is fighting Hamas in Gaza.

The American and Iranian officials interviewed for this article spoke on condition of anonymity to discuss intelligence matters.

As the proxies’ attacks intensified, culminating in the deaths of three American soldiers, Iranian leaders worried that the level of autonomy provided to the militias was starting to backfire and might drive them into war, according to Iranian and American officials.

“They are scared of direct confrontation with the U.S., they know that if Americans are killed again it would mean war,” said Sina Azodi, a lecturer at George Washington University and an expert on Iran’s national security. “They had to put the brakes on the militia and convince them that a war with the U.S. could harm Tehran first and then by extension the entire axis.”

Iran finances, arms and provides technical support and training for a network of militant groups in the region that it calls the Axis of Resistance.

The groups include Hezbollah in Lebanon; the Houthis in Yemen; militias in Iraq, such as Kataib Hezbollah and Hashd al-Shaabi; Hamas and Islamic Jihad in Gaza; and militias in Syria. While Iran directs an overall strategy to the axis, the level of day-to-day control and coordination runs a spectrum. Tehran has most influence over Hezbollah, with the Syrian and Iraqi militia falling in the middle and the Houthis being the most autonomous.

The Iranian effort to rein in the forces began soon after the killing of the three American soldiers in a drone attack in Jordan on Jan. 28, as Washington vowed a forceful response.

Gen. Qassim Suleimani, the high-level Iranian general killed by an American drone strike in 2020, kept the Shiite militias in Iraq and Syria on a tight leash. That was largely because, for most of his tenure, war was raging in both countries, and he commanded the militia to fight Americans and then Islamic State terrorist groups. But when Brig. Gen. Esmail Ghaani succeeded him, most of those conflicts had settled, and General Ghaani assumed a hands-off leadership style, setting only broad directions, according to analysts.

General Ghaani, commander in chief of the Quds Forces, the branch of the Islamic Revolutionary Guards Corps tasked with overseeing the proxies, has nonetheless been involved in coordinating the strategy toward Israel and the United States for the various militias during the current war in Gaza.

He led a series of emergency meetings in late January in Tehran and Baghdad with strategists, senior commanders of the Revolutionary Guards and senior commanders of the militia to redraw plans and avert war with the United States, according to two Iranians affiliated with the Guards, one of them a military strategist. Reuters first reported on the general’s visit to Baghdad.

In Baghdad, General Ghaani held a long meeting with representatives of all the Shia militant groups who operate under the umbrella of a collective they call Islamic Resistance in Iraq. The collective had been carrying out and then claiming responsibility for dozens of attacks on American bases, and Washington blamed the group for the drone attack that killed the Americans.

General Ghaani told them that Iran and the various militia groups had made enough gains in pressuring the United States because President Biden was facing intense criticism for his staunch support of Israel and fissures had emerged between him and Prime Minister Benjamin Netanyahu of Israel, the two Iranians affiliated with the Guards said. A war between Tehran and Washington could also jeopardize the long-term goal of rooting out the United States from the region, he told the group, the two Iranians said.

Two of the larger Iraqi militias, Kataib Hezbollah and Harakat al-Nujaba, at first fiercely resisted General Ghaani’s demand that they pause attacks on Americans, arguing that fighting U.S. troops was integral to their ideology and identity, the two Iranians said.