President Donald Trump's top national security advisers have briefed members of Congress, making the case for the US-Israel war on Iran as lawmakers from both parties seek further details.
Secretary of State Marco Rubio, Defence Secretary Pete Hegseth, CIA Director John Ratcliffe and General Dan Caine, chairman of the Joint Chiefs of Staff, held briefings for the full Senate and later the House of Representatives.
While Republicans hold narrow majorities in both chambers and have largely supported Trump's agenda, the attacks have prompted some members of his party to join Democrats in questioning whether the president should send US forces into combat without congressional approval.
Others said they wanted more information, particularly if the White House seeks additional funding.
"America First was supposed to be a rejection of the globalist war machine," Republican Representative Warren Davidson wrote on X.
"I look forward to seeing the intelligence the administration found so persuasive, then voting."
Senator Angus King, an independent who caucuses with Democrats, raised concerns during an Armed Services Committee hearing.
"Have we now delegated the most solemn decision that can be made in our society, the decision to go to war, to another country," King asked.
Clamour for more information
Rubio said on Monday that the US had acted after Israel planned to strike Iran, a remark that drew scrutiny from some lawmakers.
Senate Republican leader John Thune and House Speaker Mike Johnson said it was too early to determine whether Congress would consider a supplemental funding bill.
Johnson said further details were needed, including the duration of the operation and financial requirements.
Democrats signalled opposition to funding without formal authorisation.
House Democratic leader Hakeem Jeffries said Trump should obtain Congress' consent before requesting funds.
"There is a requirement under the Constitution that it is members of Congress that make the decision as to whether to get us entangled in this kind of armed conflict," Jeffries said.
The Senate is expected to vote on Wednesday and the House on Thursday on war powers resolutions seeking to block continued military action without authorisation.
Previous efforts to pass such measures have failed, and any resolution would require a two-thirds majority to override a presidential veto.
