In the last week the U.S. has provided Israel with tank rounds and illumination rounds for grenade launchers requested as part of a foreign military arms sale. The weapons came from a $1 billion stockpile of ammunition stored by the U.S. military in Israel for that country's use if needed for an emergency.

However, a U.S. defense official stressed the delivery of weapons from the existing stockpile in Israel was more a matter of convenience to rotate U.S. ammunition stocks than an emergency request from Israel.

Since the 1990's U.S. European Command has maintained a little -known stockpile inside Israel officially known as War Reserve Stockpile Ammunition-Israel (WRSA-I). While ostensibly for use by U.S. or Israeli forces the stockpile is essentially available for Israel's use if it makes a request for an emergency foreign military sale. Such an emergency sale can be authorized by the president as was the case in 2006 while Israel was conducting its war against Hezbollah in Lebanon.

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On July 20 Israel made a foreign military sales request for munitions that included an undisclosed amount of 120 mm tank rounds and 40 mm illumination rounds for grenade launchers. The defense official said the ammunition was sold to Israel as a "routine" foreign military sales request and not an emergency request to tap into the U.S. military stockpile in Israel.

The Israeli request to purchase the ammunition was made just days after Israel launched its ground offensive into Gaza. The fighting in Gaza since has resulted in the deaths of 1,340 Palestinians and 59 Israelis, according to the Palestinian Health Ministry. More than 7,200 have been injured.

In a statement, Pentagon spokesman Rear Admiral John Kirby confirmed the transfer of the two requested munitions from the stockpile

"Both munitions had been in WRSA-I stock for a few years, well before the current crisis," said Kirby. All stocks in WRSA-I, as required by law, are "in excess to U.S. requirements." Issuing munitions from the WRSA-I stockpile was "strictly a sourcing decision and White House approval was not required."

Kirby said the United States is committed to Israel's security "and it is vital to U.S. national interests to assist Israel to develop and maintain a strong and ready self-defense capability. This defense sale is consistent with those objectives."

A U.S. defense official told ABC News the requested ammunition was approaching the end of its shelf life at the stockpile and would have needed to be restocked anyway.

The location of the stockpile as well as the types and quantities of ammunition it stores are classified. Howeve r, a Congressional Research Service report from April says "the United States stores missiles, armored vehicles and artillery ammunition" in the stockpile.

The Congressional Research Service Report says "the government of Israel pays for approximately 90 percent of transportation, storage and maintenance costs associated with the WRSA-I program."

Editor's Note: This story has been updated after Pentagon officials corrected their initial information about the two types of ammunition sold to Israel. They had initially described the sale as including 140mm mortar rounds and 40mm grenades, they are in fact 14omm tank rounds and 40 mm illumination grenades.