The Senate could vote this week on a provision that would undo a key aspect of the military agreement with Israel negotiated last year under former President Barack Obama.

Sen. Lindsey Graham, R-S.C., has filed an amendment to the annual defense bill that would allow Israel to continue to spend more than a quarter of US military assistance to buy equipment from domestic, rather than US, firms. The amendment would represent a payday of more than $8.5 billion for the Israeli defense sector, but some critics say it would put the entire 10-year, $38 billion agreement in jeopardy.

Under last year’s memorandum of understanding for fiscal years 2019 through 2028, Israel would get $33 billion in foreign military financing and $5 billion for missile defense assistance, up from $31 billion in foreign military financing currently. In exchange, however, Israel would lose a special privilege that had allowed it to use 26.3% of its foreign military financing assistance domestically on non-US firms. Graham’s amendment would reinstate that so-called off-shore procurement rate.

At the time the deal was signed, the Obama administration argued that requiring Israel to use 100% of its foreign military financing funds on US weapons and defense systems would make Israel more secure.