Israeli assumptions about unshakeable American backing have been jolted by the US midterm results, with politicians and analysts warning of a generational shift in the alliance that long anchored Israel's security planning.

As Democratic victories piled up, Israeli opposition figures blamed Prime Minister Benjamin Netanyahu, with one saying the results showed how toxic he had become among Democrats and Republicans alike. A prominent column in a major Israeli daily called the moment a "generational sea change" and said the Netanyahu government had sown the wind and reaped a tsunami. A US official familiar with the debate said Israel's establishment understood intellectually that opinion was moving, but not how far or how fast.

The Iran war and Israel's conduct in Gaza and the occupied West Bank were campaign issues across American races. Trump himself blamed the Iran conflict for the Republican rout, a war Israeli leaders are widely seen as having encouraged. Vice President JD Vance listed the US relationship with Israel among four reasons voters deserted the party, a signal that unsettled Israeli security voices who now fear Republican as well as Democratic pressure.

Shock deepened when Trump said this week that Washington would stop about $3.8bn a year in military aid to Israel by year end, earlier than previously planned. Israel's president called the remark a bolt from the blue. Netanyahu's office later cast a shift from aid toward partnership as proof of strength, but defence analysts noted that American aircraft, spare parts and missile defence supplies remain central to Israeli war planning. A Democrat controlled Congress can slow sales and joint projects even if it lacks the votes to override a presidential veto.

Israeli and American officials still insist the core relationship will endure. Ambassadors on both sides have publicly played down talk of rupture. The midterms nonetheless leave Jerusalem planning for harder scrutiny, slower arms pipelines and less automatic diplomatic cover than Israeli governments treated as routine for a generation.