Story highlights US, Israel reach deal worth as much as $38 billion

Secret negotiations over military aid took months

Washington (CNN) The Obama administration is upping aid to Israel as part of the largest pledge of military assistance in US history.

Israel is set to get about $38 billion over 10 years, according to congressional and administration sources, up from the approximately $30 billion decade-long deal that expires in 2018.

The Memorandum of Understanding sealing the arrangement will be signed Wednesday at the State Department.

Talks to reach an agreement took months, unfolding behind closed doors at a time when US-Israel ties were strained by tensions between President Barack Obama and Prime Minister Benjamin Netanyahu and Israeli frustration over the nuclear pact with Iran

JUST WATCHED The Iran nuclear deal: One year later Replay More Videos ... MUST WATCH The Iran nuclear deal: One year later 01:24

"It's an important message to the region that nobody should misread the differences between the US and Israel when it comes to Iran or policy differences when it comes to the Palestinians," said David Makovsky, director of the Project on the Middle East Peace Process at the Washington Institute for Near East Policy. "At the core, the US remains very committed to Israel's long-term security."

Read More