The United States is sending an advanced anti-missile system to Israel, the Pentagon has announced, as President Joe Biden’s administration continues to provide “ironclad” support for one of its top allies amid mounting tensions with Iran.

The US Department of Defense said on Sunday that Pentagon chief Lloyd Austin had authorised the deployment of a Terminal High Altitude Area Defense (THAAD) “battery and associated crew of US military personnel to Israel” to help boost the country’s air defences.

“The THAAD Battery will augment Israel’s integrated air defense system. This action underscores the United States’ ironclad commitment to the defense of Israel, and to defend Americans in Israel, from any further ballistic missile attacks by Iran,” the Pentagon said in a statement.

The announcement comes less than two weeks after Iran fired a barrage of missiles at Israel on October 1 in retaliation for the assassinations of Hamas and Hezbollah leaders and an Iranian general.

Israeli leaders, including Prime Minister Benjamin Netanyahu, have vowed to retaliate — spurring fears that the Middle East could be dragged into an all-out regional war.

Earlier this month, Biden suggested that Israel should refrain from striking Iran’s nuclear facilities or oilfields, but the Israeli government has repeatedly defied the US president’s public warnings in the past.

It is unclear when exactly the US’s THAAD system will be deployed to Israel. An unnamed US official told CBS News that “around 100 troops” will go to the country.

Earlier on Sunday, Iranian Foreign Minister Abbas Araghchi warned that Washington was “putting [the] lives of its troops at risk by deploying them to operate US missile systems in Israel”.

“While we have made tremendous efforts in recent days to contain an all-out war in our region, I say it clearly that we have no red lines in defending our people and interests,” Araghchi wrote on social media.

While the US has said it favours diplomacy and a de-escalation in the region, critics have noted that Washington offers Israel unwavering military and diplomatic support.

The US provides Israel with at least $3.8bn in military aid annually, and the Biden administration has authorised $14bn in further assistance to its ally since the Israeli military began its war on the Gaza Strip in October of last year.

Israel also recently expanded its bombing campaign in Lebanon, after exchanging fire with Lebanese group Hezbollah across the Israel-Lebanon border for months.

Yet despite growing concerns over a widening war, the Biden administration has rebuffed calls to suspend weapons transfers to Israel to pressure the country to end the wars in Gaza and Lebanon.

Marwan Bishara, Al Jazeera’s senior political analyst, said “there is no doubt” that Washington’s THAAD system announcement on Sunday would further escalate regional tensions.

“I am not sure if President Biden is sleep-walking his way into another regional war … or [if] he has his eyes wide open as he escalates the war,” Bishara said.

Israel already uses three integrated missile defence systems to intercept incoming rockets and missiles fired towards the country.

But the THAAD system that the US will deploy to Israel has a greater range than other systems and marks a “step up”, Al Jazeera’s Mike Hanna reported from Washington, DC.

“The important point, too, is that the [THAAD] systems are so complex that it requires a crew of 94 to operate — a trained crew of 94 — and these will be US soldiers,” Hanna said.

“This is a system being put in place and it is a significant step up of the US support for Israel as this crisis continues.”

Speaking to Al Jazeera, military analyst Elijah Magnier said he believed the THAAD system announcement meant that the expected Israeli attack on Iran is “not imminent”, as Israel would want the missile defence system to be in place before any attack, which will likely be followed by another Iranian attack on Israel.

The US previously deployed a THAAD battery to Israel in 2019 for training and an air defence exercise, the Pentagon said on Sunday.

Biden also directed the military to send one to the Middle East “to defend American troops and interests in the region” after last year’s October 7 attacks by Hamas on southern Israel.