The United States will provide Israel's military with $38 billion during the next 10 years, officials said, on 14 September. This is the largest batch of military assistance the US has ever pledged to another country.
Following months of behind-the-scenes negotiations, the State Department said the two countries had reached a 10-year agreement, with a signing ceremony planned tomorrow.
The US and Israel haven't disclosed the exact sum, but officials familiar with the deal said it totals $3.8 billion a year, up from the $3.1 billion the US gave Israel annually under the previous 10-year deal.
Obama's national security adviser, Susan Rice, plans to attend the ceremony at the State Department, a senior Obama administration official said.
Israel's acting national security adviser, Jacob Nagel, arrived in Washington ahead of the announcement and was also expected to attend. Israel's government had no immediate comment on the deal.
Under the agreement, Israel's ability to spend part of the funds on Israeli military products will be gradually phased out, eventually requiring all the funds to be spent on American military industries.
Israel's preference for spending some of the funds internally had been a major sticking point in the deal.
The new agreement also eliminates Israel's ability to spend a fraction of the funds on fuel for its military.
In another apparent concession, Israel has agreed not to ask the Congress to approve more funds than are included in the deal, said the officials, who weren't authorised to discuss the details publicly ahead of a formal announcement and requested anonymity.
The agreement concludes many months of negotiations that involved a delicate calculation by Jerusalem about whether to strike a deal with the outgoing US president.
In February, Prime Minister Benjamin Netanyahu quietly floated the prospect of waiting for Obama's successor in hopes of securing a better deal.
But the Obama administration has been eager to lock in the agreement before leaving office to help bolster Obama's legacy and undercut the criticism that his administration was insufficiently supportive of Israel.
Obama's relationship Netanyahu has been famously fraught for years, and ties between the countries worsened significantly when the US and world powers struck a deal with a nuclear deal with Iran.
Israel considers a nuclear-armed Iran to be an existential threat and disagreed sharply with Obama's contention that the deal actually made Israel safer by limiting Iran's nuclear programme.