A US military official said on Thursday that the stockpile, which consists of missiles, armored vehicles and artillery ammunition, was given last week.
The emergency arms depot is located at a classified site inside Israel.
The munitions are part of a program managed by the US military and called War Reserves Stock Allies-Israel (WRSA-I).
"They didn't ask for it from there but we gave it to them so we could rotate our stocks," the official said.
Washington had allowed Tel Aviv to use the same arms depot during Israel's 33-day war on Lebanon back in 2006.
Separately, US lawmakers are working on a bill that gives permission to the US government to provide millions of dollars for Israeli missile system known as Iron Dome.
On Monday, US Senate Majority Leader Harry Reid said Israel urgently needs more financial aid from the United States for its offensive against Palestinians in the Gaza Strip.
Reid, a member of the Democratic Party, warned that the Obama administration’s $225 million request to aid Israel during its current war may not be enough, as the Zionist regime continues to massacre Palestinians in Gaza.
Israel has been relentlessly pounding the besieged territory for more than three weeks. More than 1,350 Palestinians have been killed and thousands wounded, including women and children. In retaliation, Palestinian resistance fighters have fired rockets into Israel.
The Israeli military is now threatening to escalate its war on the coastal enclave by warning Palestinians in areas around the Gaza City to leave their homes.
Last week, US Defense Secretary Chuck Hagel sent a letter to congressional leadership requesting $225 million in additional US funding for Israel’s Iron Dome, which is a short-range rocket defense system designed to intercept rockets and artillery shells fired from a range of between four and 70 kilometers.
The money would be in addition to the $351 million that’s already under discussion for Iron Dome in fiscal 2015. It would bring total funding to $576 million, compared with the $176 million requested by the Pentagon for the year that begins on October 1.
Israel already receives billions of dollars of American taxpayers’ money each year. Under an existing 10-year aid agreement between Washington and Tel Aviv signed in 2007, $30 billion of American money is flowing to Israel.
The US annual military aid to Israel has been elevated from $2.4 billion to $3.1 billion through 2017 under the existing agreement.
Meanwhile, US and Israeli officials have discussed a surge in US military aid to Israel in a new aid package that would extend through 2027.