The US has agreed to provide Israel with $38 billion (£28.8 billion) of military funding, the largest such agreement in history.

After ten months of negotiations, the deal - which will run until 2028 - is set to be signed today at the US State Department in Washington D.C.

The US has included funding for Israeli missile defence programmes in the deal for the first time, pledging an annual sum of $500 million (£380 million).

Unlike the previous $30 billion (£23 billion) ten-year deal, which was agreed in 2008 and will run until 2018 and saw Israel receive an additional $5 billion in additional funding, this agreement will provide a fixed annual amount, subject to yearly congressional approval.

Israel’s spending on domestic weaponry, which made up more than a quarter of the last package, will be phased out until the country purchases all its military equipment from the US.

The new deal will also forbid Israel from spending US aid on fuel for its military.

Talks over the deal - which will come into effect in 2019 - had previously faltered over these issues, as well as disagreements about the size of the aid package.

A spokesperson for the US Department of State said the agreement “constitutes the single largest pledge of bilateral military assistance in US history.‎”

Speaking to the press on Air Force One yesterday, Eric Schultz, the White House’s principal deputy press secretary, said: “This has been a long, complicated process.

“But we believe that it’s one that’s worth it because it’s in the interests of both the United States and our greatest ally in the Middle East, Israel - one of our closest allies around the world - to reaffirm our commitment to their security.”

The American Israel Public Affairs Committee (Aipac), the largest pro-Israel lobby in the US, commended the “landmark agreement” for providing Israel with “a stable planning environment to counter mounting threats.”

The organisation added that the deal “will send a strong message of deterrence to America's and Israel's regional adversaries that these two allies stand together amid increased instability and growing chaos in the Middle East.”

Susan Rice, national security adviser for the US, spoke to the American Jewish Committee Global Forum in June about the upcoming “significant increase in support”.

She said the deal would “provide Israel the funding to update much of its fighter aircraft fleet, substantially enhance the mobility of its ground forces, and continue to strengthen its missile defense capabilities.

“That’s what we mean when we say Israel is not alone.”

Ms Rice and Yaakov Nagel, her Israeli counterpart, are expected to attend the signing ceremony.

The deal will be the third such agreement between the two countries, with the first in 1998 securing $21.3 billion in military aid for Israel.