WASHINGTON — The USA on Thursday carried out airstrikes in jap Syria in opposition to buildings belonging to what the Pentagon stated had been Iran-backed militias answerable for current assaults in opposition to American and allied personnel in Iraq.

President Biden approved the strikes in response to the rocketing in Iraq and to persevering with threats to American and coalition personnel there, stated John F. Kirby, the Pentagon press secretary, who spoke with reporters touring with Protection Secretary Lloyd J. Austin III in California.

A rocket attack on Feb. 15 on the airport in Erbil, in northern Iraq, killed a Filipino contractor with the American-led navy coalition and wounded six others, together with a Louisiana Nationwide Guard soldier and 4 American contractors.

American officers stated the strikes had been a comparatively small, fastidiously calibrated navy response: seven 500-pound bombs dropped on a small cluster of buildings at an unofficial crossing on the Syria-Iraq border used to smuggle throughout weapons and fighters.

The strikes had been simply over the border in Syria to keep away from diplomatic blowback to the Iraqi authorities. The Pentagon provided up bigger teams of targets however Mr. Biden accredited a much less aggressive possibility, American officers stated.

The American airstrikes on Thursday “particularly destroyed a number of amenities situated at a border management level utilized by a variety of Iranian-backed militia troops, together with Kataib Hezbollah and Kataib Sayyid al-Shuhada,” Mr. Kirby stated.

“This proportionate navy response was carried out along with diplomatic measures, together with session with coalition companions,” he added. “The operation sends an unambiguous message: President Biden will act to guard American and coalition personnel.”

Mr. Kirby stated the American retaliation was meant to punish the perpetrators of the rocket assault however to not escalate hostilities with Iran, with which the Biden administration has sought to resume talks on a nuclear deal that President Donald J. Trump had shelved.

“We now have acted in a deliberate method that goals to de-escalate the general scenario in each jap Syria and Iraq,” Mr. Kirby stated.

The assault on the Erbil airport was claimed by a little-known group referred to as Awliya al Dam, or Guardian of the Blood, brigades. The group additionally claimed accountability for 2 bombings in opposition to U.S. contractor convoys in August.

Little is thought concerning the group, together with whether or not it’s backed by Iran or associated to the organizations that used the amenities the American airstrikes focused on Thursday. Some American officers contend that the group is merely a entrance for one of many better-known Shia militias.

Michael P. Mulroy, a former high Center East coverage official on the Pentagon, stated the restricted strikes appeared meant to sign that Iran’s use of militias as proxies wouldn’t enable them to keep away from accountability for attacking People. However the time and place of the assault additionally had been important.

“The choice to strike in Syria as a substitute of Iraq was prone to keep away from inflicting points for the Iraqi authorities, a key companion within the persevering with efforts in opposition to ISIS,” Mr. Mulroy stated in an e-mail. “It was sensible to strike in Syria and keep away from the blowback in Iraq.”

Mr. Biden had mentioned the rocket assaults in a cellphone name on Tuesday with Prime Minister Mustafa al-Kadhimi of Iraq. A White Home assertion afterward stated that the 2 agreed “that these answerable for such assaults should be held absolutely to account.”

The retaliatory strikes, which happened about 6 p.m. Thursday in Washington, or 2 a.m. Friday in jap Syria, had been within the works for a number of days as American intelligence businesses labored to determine excessive confidence that the 2 Iraqi militia had been answerable for the rocket assaults.

American officers stated the assault killed a “handful” of militia, however the Pentagon didn’t present any detailed evaluation of the harm.

Saberin Information Telegram channel, which is affiliated with Iranian-backed militia in Iraq, reported one lifeless and several other injured. It stated the strikes focused an empty constructing and one other construction utilized by the militia. The bases had been in an space between Al Qaem and Abu Kamal, close to the Syria-Iraq border.

Mr. Biden approved the strikes on Thursday morning, as his protection secretary was at a lodge in San Diego, getting ready to go to the plane service Nimitz, which was returning home from the Persian Gulf.

Mr. Austin expressed confidence that the amenities focused had been utilized by militia teams answerable for the assaults. Talking to reporters aboard his aircraft Thursday night, he stated that the Biden administration had been “deliberate” in its strategy.

“We allowed and inspired the Iraqis to analyze and develop intelligence and it was very useful to us in refining the goal,” he stated.

The Biden administration has taken a extra measured response to the rocket fusillade in Erbil than Mr. Trump’s pitched marketing campaign in opposition to Iran and previous actions of its proxies in Iraq — one that usually caught the Iraqi authorities within the crossfire.

Administration officers have stated for the reason that Erbil assault that the USA would reply to the strike at a time and place of its selecting.

Even so, the deliberateness of the brand new administration’s strategy has raised questions each in Washington and in Baghdad about where Mr. Biden’s red lines are in the case of responding to assaults from Iranian-backed militias that focus on People in Iraq.

The USA navy has drawn down the variety of its troops in Iraq to underneath 2,500 and has pulled out of a number of bases there over the previous two years. It says Iraq now not wants the assistance it did up to now to struggle the Islamic State, although American officers have acknowledged that militia assaults additionally factored into the choice to maneuver troops to bases extra simply defended.

Iran has made clear that it intends to retaliate additional for the American drone strike in Baghdad in January 2020 that killed a top Iranian commander, Maj. Gen. Qassim Suleimani, and a senior Iraqi safety official. Days after that strike, the Iranian authorities launched missile attacks in opposition to U.S. forces on the Ain al Assad air base in Iraq’s Anbar Province, wounding greater than 100 troops.

Julian E. Barnes contributed reporting from Washington, and Farnaz Fassihi from New York.