The United States has spent a record of at least $17.9 billion on military aid to Israel since the war on Gaza began and led to escalating conflict around West Asia, according to a report for Brown University’s Costs of War project, released on Monday on the anniversary of Hamas’s attacks on Israel.

An additional $4.86 billion has gone into stepped-up U.S. military operations in the region since the October 7, 2023, attacks, researchers said. That included the costs of a Navy-led campaign to quell strikes on commercial shipping by Yemen’s Houthis, who are carrying them out in solidarity with the fellow Iranian-backed group Hamas.

The report — completed before Israel opened a second front — against Iranian-backed Hezbollah militants in Lebanon, in late September — is one of the first tallies of estimated U.S. costs as the President Joe Biden’s administration backs Israel in its conflicts in Gaza and Lebanon and seeks to contain hostilities by Iran-allied armed groups in the region.

The financial toll is on top of the cost in human lives: Hamas militants killed more than 1,200 people in Israel a year ago and took 250 others hostage. Israel’s retaliatory offensive has killed nearly 42,000 people in Gaza, according to the territory’s Health Ministry.

At least 1,400 people in Lebanon, including Hezbollah fighters and civilians, have been killed since Israel greatly expanded its strikes in that country in late September.

The financial costs were calculated by Linda J. Bilmes, a professor at Harvard’s John F. Kennedy School of Government, who has assessed the full costs of U.S. wars since the September 11, 2001, attacks, and fellow researchers William D. Hartung and Stephen Semler.

Israel — a protege of the United States since its 1948 founding — is the biggest recipient of U.S. military aid in history, getting $251.2 billion in inflation-adjusted dollars since 1959, the report said.

Even so, the $17.9 billion spent since October 7, 2023, in inflation-adjusted dollars, is by far the most military aid sent to Israel in one year. The U.S. committed to providing billions in military assistance to Israel and Egypt each year when they signed their 1979 U.S.-brokered peace treaty, and an agreement since the Obama administration set the annual amount for Israel at $3.8 billion through 2028.

The U.S. aid since the Gaza war started includes military financing, arms sales, at least $4.4 billion in drawdowns from U.S. stockpiles and hand-me-downs of used equipment.

Much of the U.S. weapons delivered in the year were munitions, from artillery shells to 2,000-pound bunker-busters and precision-guided bombs.

Expenditures range from $4 billion to replenish Israel’s Iron Dome and David’s Sling missile defence systems to cash for rifles and jet fuel, the study said.

Unlike the U.S.’s publicly documented military aid to Ukraine, it was impossible to get the full details of what the U.S. has shipped Israel since last October 7, so the $17.9 billion for the year is a partial figure, the researchers said.

They cited Biden administration “efforts to hide the full amounts of aid and types of systems through bureaucratic maneuvering.”

‘Divided’ society

Funding for the key U.S. ally during a war that has exacted a heavy toll on civilians has divided Americans during the ongoing presidential campaign.

But support for Israel has long carried weight in U.S. politics, and Mr. Biden said on Friday that “no administration has helped Israel more than I have.”

The Biden administration has bolstered its military strength in the region since the war in Gaza started, aiming at deterring and responding to any attacks on Israeli and American forces.

Those additional operations cost at least $4.86 billion, the report said, not including beefed-up U.S. military aid to Egypt and other partners in the region. U.S.

The U.S. had 34,000 forces in West Asia the day that Hamas broke through Israeli barricades around Gaza to attack. That number rose to about 50,000 in August when two aircraft carriers were in the region, aiming at discouraging retaliation after a strike attributed to Israel killed Hamas political leader Ismail Haniyeh in Iran. The total is now around 43,000.

The number of U.S. vessels and aircraft deployed — aircraft carrier strike groups, an amphibious ready group, fighter squadrons, and air defence batteries — in the Mediterranean, Red Sea and Gulf of Aden has varied during the year.

The Pentagon has said another aircraft carrier strike group is headed to Europe very soon and that could increase the troop total again if two carriers are again in the region at the same time.

The U.S. military has deployed since the start of the war to try to counter escalated strikes by the Houthis, an armed faction that controls Yemen’s capital and northern areas. The researchers called the $4.86 billion cost to the U.S. an “unexpectedly complicated and asymmetrically expensive challenge.”

Houthis have kept launching attacks on ships traversing the critical trade route, drawing U.S. strikes on launch sites and other targets.

The campaign has become the most intense running sea battle the U.S. Navy has faced since the Second World War.

“The U.S. has deployed multiple aircraft carriers, destroyers, cruisers and expensive multimillion-dollar missiles against cheap Iranian-made Houthi drones that cost $2,000,” the authors said.

The researchers’ calculations included at least $55 million in additional combat pay from the intensified operations in the region.