A senior Israeli official is on his way to Washington for what is expected to be the last round of negotiations over the latest military aid package from the US to Israel. The 10-year, $38 billion defense package, known as the Memorandum of Understanding (MOU), will be the biggest American foreign aid package in the country’s history.

Brig. Gen. (res.) Yaakov Nagel, acting head of the National Security Council, was set to leave Israel on Sunday for a round of meetings with counterpart US National Security Adviser Susan Rice. According to senior administration officials, the deal will be completed by the end of Nagel’s visit.

Talks over the new defense deal, which could top $40 billion over the next decade, have been ongoing for months, with American lawmakers fighting over the size of the aid package in addition to diplomatic considerations between Israel and the US.

The new deal, while boasting a bigger price tag than the previous MOU with an increase of about $4 billion, comes at a cost: it limits the amount of money Israel can spend domestically. By the end of the next ten years, Israel will be forced to spend virtually all of the aid in the US, which would hurt Israel’s own defense industry.

However, Israeli Prime Minister Benjamin Netanyahu, under pressure from the US, has said he would like to sign the deal with the current administration, rather than wait for the next US president in hopes of getting better terms.