"This reprogramming action provides funding for the replacement of defense articles from the stocks of the Department of Defense expended in support of Israel or identified and notified to Congress for provision to Israel," the document said.
The budget document dated August 1, is titled Israel Security Replacement Transfer Fund Tranche 9, and requested $498.265 million in funding for THAAD systems alone.
“Funds are required for the procurement of replacement THAAD Interceptors expended in support of Israel. This is a congressional special interest item. This is an emergency budget requirement,” the document said.
The War Zone reported that the US fired more than 150 THAAD missiles during the Iran war alone.
The publication also said details of US bombings of Iranian nuclear facilities, known as Operation Midnight Hammer, are only just coming to light now, though the full cost is still unknown.
The US announced it had deployed THAAD defences in Israel in October, more than a year after the Gaza war broke out, seeing Iran's allies in the region firing on the Jewish state from Lebanon, Yemen, Iraq and Syria.
It also came after Iran's second direct attack on Israel when hundreds of missiles and drones were fired in a massive aerial barrage.
"This reprogramming action addresses funds for the replacement of defense articles expended in support of Israel through US combat operations executed at the request of and in coordination with Israel and for the defense of Israeli territory, personnel, or assets during attacks by Iran, and subsequent or anticipated attacks by Iran and its proxies," the document said.
The documents show the extent of the cost of the US military's defense of Israel and also the cost of weapons that American forces used during their extensive bombing of Iran’s three main nuclear facilities in June, Natanz, Fordow and Isfahan.
Among the funds requested were those to "replace GBU-39s expended during Operation Midnight Hammer in support of Israel", the document detailed. "This is a congressional special interest item. This is an emergency budget requirement."
Made by US defense contractor, Lockheed Martin, THADD intercepts short, medium and intermediate-range ballistic missiles, engaging targets directly at ranges of 93 to 124 miles both inside and outside the atmosphere.
Each THAAD battery system requires around 100 soldiers, and has been used to help defend Israel from ballistic missiles from both Iran and its military ally, the Houthis, in Yemen.
US Missile Defense Agency documents say that each THAAD interceptor costs roughly $12.7 million, and now there are concerns about insufficient American stockpiles.
In addition to Iranian attacks, Israel says dozens of drones and ballistic missiles have been fired from Yemen to Israel since the outbreak of the Gaza war. The Iran-backed Houthis say their actions are in allegiance with Iran’s ally Hamas in Gaza.
During the 12-day war in June, Iran fired over 500 ballistic missiles in response to Israel’s surprise attacks on June 13, in which dozens of military and nuclear figures were killed.