A group of 12 US Senators proposed on Thursday legislation that would ensure American military aid to Israel would not be used to fund Prime Minister Benjamin Netanyahu's annexation plans in the latest effort in Congress to oppose the looming Israeli move. The legislators proposed an amendment to the US defence budget for 2021 that would prohibit the use of American funds "to deploy defense articles, services or training" in annexed territories in the West Bank or to facilitate their annexation. Chris Van Hollen introduced the proposal, which was backed by key Democrats, including Elizabeth Warren, Sherrod Brown, Tim Kaine, Chris Murphy, Tammy Baldwin, Jeff Merkley and Patrick Leahy as well as independent progressive leader Bernie Sanders. Van Hollen slammed annexation in a 38-minute speech on the Senate floor on Thursday, detailing how Israel's plans would end the prospects of the two-state solution and harm US interests in the region. "It will harm our national security interests and credibility by undermining the fundamental principles of international law that we, the United States, have championed since the end of World War Two," Van Hollen said of Israel's plan for unilateral annexation. International law Israel receives $3.8bn in US aid each year, in accordance with a memorandum of understanding signed by then President Barack Obama in 2016. Thursday's amendment comes two days after 13 progressive US legislators, including Sanders and Alexandria Ocasio-Cortez, sent a letter to Secretary of State Mike Pompeo vowing to impose conditions on US assistance to Israel if it proceeds with its annexation plans. Netanyahu's government had set a 1 July deadline to start the process of annexing parts of the West Bank, but by Thursday evening it had not made any announcements on the matter amid global outrage. Israel captured the West Bank, including East Jerusalem, in the 1967 war. Since then, it has maintained military control and built settlements in the territory in violation of international law that prohibits occupying powers from transferring their civilian population to occupied areas.