White House press secretary Jen Psaki told reporters on Friday that US President Joe Biden's air strike on Iran-backed militias in Syria was meant to send an "unambiguous message" that "he's going to act to protect Americans".
But while this is drawing rare praise from key Republican leaders in Congress, some Democratic politicians are questioning the legality of Mr Biden's actions.
"As the Iranian regime continues to test American resolve under a new administration, establishing and maintaining credible deterrence is critical," James Risch, the top Republican on the Senate foreign relations committee, said.
“After several unanswered attacks against US interests, I welcome the administration’s decision to authorise air strikes against Iranian-backed militias operating in eastern Syria.”
Mr Biden launched the strike on Thursday on Bukamal, near the Syria-Iraq border, targeting infrastructure belonging to the Iraqi militias Kataib Hezbollah and Kataib Sayyid Al Shuhada, killing at least one person and injuring several others.
The White House said “the targets were chosen to correspond to the recent attacks” on US forces in Iraq and to “deter the risk of additional attacks over the coming weeks".
Kataib Hezbollah has denied responsibility for the attacks on US forces in Iraq over the past several days.
Saraya Awliya Al Dam, a small Iran-backed militia, claimed credit for the rocket attack on US forces in Erbil on February 15 that killed a Filipino military contractor and injured several other people.
But the Biden administration has not indicated that it has targeted any forces affiliated with the group.
Nonetheless, Michael McCaul, the top Republican on the House foreign affairs committee, thanked "the president and our service members for protecting Americans overseas.
“I called for the administration to respond to the recent attacks on US and coalition targets, and I commend them for doing just that,” said Mr McCaul.
“Responses like this are a necessary deterrent and remind Iran, its proxies and our adversaries around the world that attacks on US interests will not be tolerated.”
In contrast, some high-profile Democratic allies of the president questioned the legality of the strike under US law.
"The American people deserve to hear the administration's rationale for these strikes and its legal justification for acting without coming to Congress," Tim Kaine, a senator from Virginia, said.
“Offensive military action without congressional approval is not constitutional, absent extraordinary circumstances. Congress must be fully briefed on this matter expeditiously.”
The White House has announced that it will brief Congress on the strike early next week – or sooner if requested.
“The Department of Defence briefed congressional leadership before the action last night,” said Ms Psaki.
“The administration has been briefing the Hill at the member and staff level today. There will be a full classified briefing early next week at the latest.”
The White House argues that the strikes were legal as an act of self-defence under US and international law.
But Mr Biden’s Democratic critics indicated that they view the attacks as offensive.
This echoes arguments they made when the Trump administration struck several Iran-backed militias in retaliation for attacks on US forces in Iraq.
This culminated in the death of Islamic Revolutionary Guard Corps' Quds Force commander Maj Gen Qassem Suleimani and Abu Mahdi Al Muhandis, leader of Iraqi militia organisation the Popular Mobilisation Forces.
"The strikes by Iranian-backed militias on bases in Iraq hosting US troops are unacceptable, and the president unquestionably has the right to defend our nation and our armed forces from imminent attack," Chris Murphy, chairman of the Senate's Middle East panel, said.
“But retaliatory strikes not necessary to prevent an imminent threat must fall within the definition of an existing congressional authorisation of military force.”
“Congress should hold this administration to the same standard it did prior administrations and require clear legal justifications for military actions, especially inside theatres like Syria, where Congress has not explicitly authorised any American military action,” Mr Murphy said.
Nonetheless, Mr Biden's Syria strike did gain support from at least one key Democratic leader – House armed services committee chairman Adam Smith, who classified the move as "defensive".
"Last night's strike should serve as a reminder that the United States will always defend our partners, allies, interests and ourselves," Mr Smith said.
“This strike against an Iranian-backed militia was defensive in nature, following multiple rocket attacks against our forces in Iraq.”