Protesters calling for a ceasefire in Gaza interrupted US Secretary of State Antony Blinken during a Senate hearing on Tuesday.
Numerous people stood in the crowd and repeatedly yelled "Ceasefire now!"
Secretary Blinken and US Defense Secretary Lloyd Austin testified about the White House's $106bn (£87.4bn) national security funding request.
It includes $14.3bn to support Israel's military efforts against Hamas.
Standing up one by one, protesters waited for Mr Blinken to begin his testimony before shouting over him again. The Secretary of State paused and lawmakers were forced to suspend the hearing several times.
Capitol Police quickly escorted the demonstrators from the room. Police said 12 people had been arrested for illegally protesting inside the Dirksen Senate Office Building.
Some of those who interrupted the proceedings were affiliated with the anti-war group CODEPINK, which has also called for the US to stop sending weapons to Ukraine.
Many protesters wore pink and held signs reading "No to the siege of Gaza", as they called for the US to stop sending funds to Israel.
CODEPINK confirmed that some of its members were arrested. Some had painted their hands red "to symbolise blood", the group said.
Mr Blinken acknowledged the protesters and "the passions expressed in this room" at the end of his statement.
"All of us are committed to the protection of civilian life. All of us know the suffering that is taking place as we speak, all of us are determined to see it end," he said.
He added, however, that it was imperative that the US stand with its allies.
Mr Blinken and Mr Austin are lobbying for lawmakers to support President Joe Biden's national security package, which also includes:
$61.4bn for Ukraine's defence
$9.2bn for humanitarian assistance
$2bn for Indo-Pacific security
$10.9bn for southern border security and migrant issues
As support for Ukraine has diminished among conservative voters, Congressional Republicans have increasingly said they want to consider Israel as a separate funding request.
Mike Johnson, the newly elected Speaker of the House of Representatives, has proposed legislation that would send $14.3bn in emergency funding to Israel.
It is not connected to the White House's other national security priorities and would strip the same amount from the budget of the Internal Revenue Service, the agency in charge of collecting federal taxes.
The new Speaker defended his bill on Fox News and said Americans would "say standing with Israel and protecting the innocent over there is in our national interest and is a more immediate need than IRS agents".
The White House said Republicans were using the crisis to "help the wealthy and big corporations cheat on their taxes".
"Politicising our national security interests is a non-starter," White House press secretary Karine Jean-Pierre said in a statement.
Rep Debbie Wasserman-Schultz, a Democrat with strong ties to Israel, said she was "deeply disturbed" by Mr Johnson's bill and said his "political games are offensive to all pro-Israel Americans".
The US has a long history of supporting Israel. It has provided the country with $158bn since World War Two, largely in military aid, according to the Congressional Research Service.
The White House and senior American officials have reaffirmed US support for Israel numerous times since Hamas's 7 October attack.
"We stand with Israel. And we will make sure Israel has what it needs to take care of its citizens, defend itself, and respond to this attack," Mr Biden said in its immediate aftermath.
In recent weeks, the president's tone has changed slightly.
He has maintained his support for Israel but also cautioned its leaders to follow international law and respond responsibly to the unfolding humanitarian crisis in Gaza affecting Palestinian civilians.
Israel says Hamas's incursion and ongoing rocket attacks since 7 October have killed 1,400 people. At least 239 people were also taken hostage by Hamas.
Israel has been bombing Gaza since the attack. The Hamas-run health ministry in Gaza says more than 8,500 people have been killed since Israel's bombardment began.
