(WASHINGTON) -- President Joe Biden is showing no signs of trying to restrict or withhold the billions the U.S. spends each year in military aid to Israel, despite growing concerns that some of those weapons are being used in bombings that kill civilians.
The U.S. has sent more military and foreign aid to Israel than any other country, including a 10-year, $38 billion program that supplies some $3.3 billion in foreign military sales to Israel each year.
U.S. officials insist that most weapons transfers since the Israeli-Hamas war began were approved long before it started and would be legally challenging to stop.
But some experts say the U.S. has the power to reverse course if it wanted to.
"There are all kinds of ways to speed up or slow down arms transfers," said retired Col. Steve Ganyard, an ABC News contributor and former deputy assistant secretary at the State Department's Bureau for Military-Political Affairs, which oversees foreign weapons sales.
"You can slow the system down to a crawl," Ganyard added. "If the administration or the Congress wanted to shut things down, they could. But it's a matter of political will."
Top Biden administration officials this week defended the approach as in line with decades of U.S. policy that's stretched across Republican and Democratic administrations. And they warned that to reverse the hundreds of open military contracts with Israel would reverse decades of U.S. policy and leave Israel vulnerable to attack from Iran.
"The security relationship we have with Israel is not just about Gaza" and the Hamas attack in Israel on Oct. 7," said Secretary of State Antony Blinken. "It's also about the threats posed Israel, by Hezbollah, by Iran, by various other actors in the region -- each one of which has vowed one way or another, to try to destroy Israel."
The question of restricting military sales grew increasingly urgent this week after an Israeli airstrike killed seven aid workers delivering food to Gaza amid a worsening humanitarian crisis. Israel said it was investigating the incident and calling it a grave mistake.
The Pentagon said it couldn't say if the weapons in the strike were American-made, but noted that Israel was expected to honor its promise to use weapons in accordance with international law.
White House National Security Council spokesman John Kirby said the administration was "outraged" by the strike and insists that Israel be more careful in its operations against Hamas. At the same time, Kirby made clear the U.S. wouldn't use military aid as leverage and "hang some sort of condition" around Israel's "neck."
"We're still gonna make sure that they can defend themselves," Kirby told reporters Tuesday.
Democrats though are split on that approach, with several close Biden allies on Capitol Hill calling for the U.S. to put more restrictions on U.S. aid even before the latest strike that killed the aid workers.
"We have a situation where the Netanyahu government continues to rebuff the president of the United States time and time again, ignores reasonable requests," said Sen. Chris Van Hollen, a Maryland Democrat, in an interview Sunday with ABC's "This Week."
"And what do we do? We say we're going to send more bombs," Van Hollen said.
Van Hollen and other Democrats have been investigating legislation on the matter, although it's not clear such a measure would gather enough support to pass or overcome a presidential veto.
Josh Paul, a former senior State Department official and outspoken critic of Biden's policy toward Israel, told ABC News that there was consensus among an internal working group before he resigned from the State Department that found Israel violated legal requirements to receive U.S. aid.
Under the law, the U.S. can't supply military aid or training to countries that violate human rights. Biden has also specified that aid shouldn't go to countries that "more likely than not" are used to commit or facilitate genocide or break international law.
"We could never get anyone from the political level of the department to move the paperwork -- because it would have consequences for their careers," said Paul, former director of congressional and public affairs for the State Department's Bureau of Military Affairs.
"There is a willingness and ability to take this on the working level but at the political level it gets killed," he said.
Paul said he understands the U.S. is having tough conversations with Israel behind closed doors.
But "at the same time we are having those conversations we are authorizing billions of dollars in military aid and I'm not sure the message is coming across," he said.
The decades-long unequivocal support in U.S. military aid for Israel seemed like it was on shaky ground last November when Biden called the idea of conditions a "worthwhile thought."
Biden noted at the time that putting restrictions on Israel's military capabilities could make it more difficult to secure the release of Israeli hostages being held by Hamas.
Since then, Biden approved two emergency transfers of military aid totaling some $254 million – bypassing Congress to rush tank munitions and related equipment to Israel.
More recently, the U.S. is considering the sale of 50 new F-15 fighter jets to Israel, according to Sen. Ben Cardin, a Maryland Democrat who chairs the Senate Foreign Relations Committee.
The first fighter jets wouldn't arrive until 2029 at the earliest.
Cardin said the proposal was aimed at helping Israel upgrade its fleet and noted the arms package -- if it happens -- would go through the usual procedures before approval.
"It has nothing to do with the current conflict in Gaza," Cardin said.
ABC News' Selina Wang, Luis Martinez and Shannon Crawford contributed to this report.