The Biden administration has begun delivering munitions and military equipment to Israel amid its war with the Hamas terrorist group.
The Pentagon is also reviewing inventories to see what can quickly be sent to boost Israel's military capabilities, a senior Defense Department official told The Associated Press.
The movement of weapons came as President Biden announced that 11 American citizens had been killed in the war.
Congress must pass more funding quickly for the U.S. to be able to give both Israel and Ukraine the weapons and munitions they both now need, Army Secretary Christine Wormuth said Monday.
"The intent is to lean forward in support of Israel," she said. "But in particular with munitions and the ability to support Israel and Ukraine simultaneously, additional funding is needed to increase our capacity to expand production and then also pay for the munitions themselves."
Wormuth, speaking at the annual Association of the United States Army conference in Washington, said the administration is still "in the early stage of the process of evaluating our ability to support what the IDF needs," referring to the Israel Defense Forces.
The addition of weapons for Israel ahead of a possible military ground offensive in the Gaza Strip following Saturday's surprise attack by Hamas.
In a statement, Biden said the U.S. believes it is likely that American citizens may be among those being held hostage by Hamas, but officials are working to confirm that.
"I have directed my team to work with their Israeli counterparts on every aspect of the hostage crisis, including sharing intelligence and deploying experts from across the United States government to consult with and advise Israeli counterparts on hostage recovery efforts," Biden said.
The attacks have so far left more than 1,100 dead on both sides.
In addition to Hamas, Israeli forces have had to contend with a second front in the north from Lebanon-based Hezbollah.
The defense official said there is concern that Hezbollah and other Iranian-backed groups will make the wrong decision to try to "pile on" and widen the war.
On Sunday, Defense Secretary Lloyd Austin said he has ordered the USS Gerald R. Ford carrier strike group to sail to the Eastern Mediterranean to be ready to assist Israel.
The Associated Press contributed to this report.
