The US military has spent $20 billion (13 billion pounds) on the war in Iraq and expects to spend $2 billion a month to maintain thousands of troops there through the remainder of the current financial year ending on September 30.
"The war has cost in the region of about $20 billion so far," Defence Department Comptroller Dov Zakheim told reporters at a Pentagon briefing on Wednesday.
Zakheim said personnel costs in the month-long war have approached $7 billion, combat operations slightly over $10 billion and ammunition and equipment over $3 billion.
"A rough estimate of the monthly cost of the war from here on out - a really rough estimate - is approximately $2 billion" to maintain forces in Iraq, he added, stressing that combat operations were waning sharply.
The United States has not determined how long its forces will remain in Iraq as that country struggles to form a new government.
Zakheim spoke shortly after US President George W. Bush signed into law on Wednesday a $79 billion package to pay for the war in Iraq, reward regional allies including Turkey and help struggling US airlines, a White House statement said.
The package, which Congress took up at the start of the war and pushed through in just three weeks, gave Bush the $62 billion he wanted to meet war costs, but curbed the free rein he wanted over most of the funds. But lawmakers declined to give the pentagon major flexibility in spending the funds.
In addition to the actual Iraq war costs - which include transporting more than 125,000 troops, hundreds of aircraft and dozens of warships to the region - the Pentagon is spending up to $1.2 billion monthly in the global war on terrorism sparked by the September, 2001, attacks on America, Zakheim said.
The $62 billion also includes $1.8 billion in funds for direct military aid to Pakistan and other countries supporting the war on terror.
Aside from the military package, the supplemental also provides $2.5 billion as seed money for Iraq's post-war restoration and about $8 billion in aid to reward allies, including Jordan, Egypt, Afghanistan, Israel and Pakistan.
Over initial objections from the White House, lawmakers included relief worth about $3.5 billion for U.S. airlines that lost business because of the war, and extended jobless benefits for aviation industry workers.
The bill provided $4 billion to tighten homeland security protections, including $2.2 billion to help local governments meet the rising costs of sending police, firefighters and other "first responders" to terror threats.
It also contained $100 million to help state and local health authorities with the costs of a civilian smallpox vaccination program, and $42 million to compensate volunteers who suffer adverse reactions to the vaccinations.
