Speaking during political consultations in Jerusalem on Thursday, Herzog warned that the announcement raised serious questions about Israel's security arrangements with the United States .

He also stressed the need to form a government rather than hold another election , citing the importance of maintaining relations with Washington.

"It worries me greatly, and it came upon us like a bolt from the blue. We have an MOU with the United States that is supposed to remain in force through 2028. This is one of the major objectives, and it is precisely why we need to form a government rather than go to another election. The entire issue is the United States," Herzog said.

The announcement followed Trump's statement on Tuesday that he and Prime Minister Benjamin Netanyahu had agreed months earlier to end approximately $4 billion in annual US military assistance by the end of 2026.

Trump argued that Israel no longer needed the financial support, although he said the country could continue purchasing American weapons.

However, uncertainty remains over when the assistance would actually stop.

US Ambassador to Israel Mike Huckabee said on Thursday that Washington was seeking clarification on whether the funding would end immediately or after the existing agreement expires in 2028.

The current $38 billion memorandum of understanding between Israel and the United States covers fiscal years 2019 to 2028.

Under the agreement, Israel receives $3.8 billion annually in military assistance, subject to approval by the US Congress.

Yashar party representative Shaul Meridor warned that ending the funding without sufficient preparation could disrupt Israel's defence budget and military procurement plans.

"This is not how a normal country is run. Beyond the dramatic security crisis and the major economic crisis, this is not something that can happen overnight. It will have a dramatic impact both on the upcoming budgets and on the way the IDF plans its procurement," Meridor said.

Israel's Defence Ministry had previously announced discussions in June about developing a new arrangement with Washington.

The proposed framework would gradually move away from direct military assistance towards joint investment in defence research, development and production.

The uncertainty surrounding US military aid comes as Israel continues negotiations to form a new government following its parliamentary election.

Parties representing 67 lawmakers have recommended Yashar leader Gadi Eisenkot to form the next government, compared with 46 supporting Netanyahu.

Herzog said he planned to assign the mandate on Sunday, although the recommendations do not guarantee that either candidate can secure enough parliamentary support to establish a governing coalition.