Updated at 5:20 p.m. ET.
The Pentagon has confirmed that Israel was given permission last week to dip into a little-known U.S. munitions stockpile to draw tank shells and illumination rounds for its ongoing offensive in the Gaza Strip.
NPR's Tom Bowman reports that the billion-dollar U.S. "emergency" stockpile, based on Israeli soil, was established in the 1980s as part of an agreement of expanded cooperation between the two nations.
A report from the Congressional Research Service says the cache of U.S. arms and equipment, known as the War Reserves Stock Allies-Israel (WRSA-1) program, can be used by Israel with U.S. approval. The last time the U.S. granted access to the arsenal was during the 2006 war against Hezbollah in Lebanon, CRS says.
The confirmation comes as the White House today said Israel must do more to protect civilians from harm following an Israeli artillery attack that struck a U.N. school housing hundreds of refugees, killing 15 and wounding more than 100.
Both Israel and Hamas accuse each other of a rocket attack on a U.N. hospital.
White House press secretary Josh Earnest called the shelling of civilian targets "totally unacceptable and totally indefensible."