Republican legislators grilled top Pentagon officials on Tuesday over what they perceive as a lack of response to Iranian attacks against US forces in the region.
Last Thursday, an Iranian drone attack on a US coalition base in north-eastern Syria killed an American contract worker and injured six others.
The US responded with precision air strikes on Iran-linked groups in the region that left 19 people dead, according to the Syrian Observatory for Human Rights in the UK.
But some Republican senators say the military has not responded strongly enough.
“Despite the more than 80 attacks by Iranian-backed militias, the United States has only responded with force just a handful of times. In my view, that's unacceptable,” said Senator Ted Budd.
Iran has launched 83 attacks against the US since Joe Biden became President in January 2021, according to testimony from Secretary of Defence Lloyd Austin.
The Pentagon chief clarified that many of those attacks yielded no significant damage or deaths.
“An attack can consist of a number of things,” he told the Senate Armed Services Committee. “It can consist of a rocket that's fired in the direction of one of our bases but is not effective.”
Mr Austin defended the military’s responses.
“When we respond, we want to make sure that we are going after the element that is responsible for whatever that activity is,” he said.
“So it takes a little time to develop attribution and then we want to make sure that we are holding the right element accountable, and we're doing everything that we can to protect our troops.”
But Mr Austin's comments did not satisfy Republicans.
“Seventy-nine and four is Iran’s record right now,” said Senator Tom Cotton.
“What kind of signal do we think this sends to Iran when they can attack us 83 times since Joe Biden has become president and we only respond four?"
Mr Budd said that "weakness only breeds more aggression" and that if the US only retaliated when an American is killed, Iran would "continue attacking, hoping to injure as many as possible".
The Biden administration has taken a more cautious approach to Iran than its predecessor.
Mr Biden said the US did not "seek conflict with Iran" but warned that he was prepared "to act forcefully to protect our people".
Under the administration of his predecessor, Donald Trump, the US military killed Iran's top military leader, Qassem Suleimani, in an early morning drone strike at Baghdad International Airport on January 3, 2020.
The US has about 900 troops in Syria and 2,500 in Iraq supporting the international coalition against the remnants of ISIS.
