Israel's latest move to advance the annexation of the occupied West Bank has faced a strong setback from the United States — its top ally and supporter — after US President Donald Trump drew a rare red line. He warned Israel that it "would lose all of its support from the US" if the annexation proceeds.

Trump's most stern warning yet was made to Time magazine on Oct 15 — just days after the Gaza truce plan he spearheaded took effect — but was only published on Thursday.

"It won't happen," Trump said when asked about calls in Israel to annex the West Bank, which has been occupied by Israel since 1967. "It won't happen because I gave my word to the Arab countries. Israel would lose all of its support from the United States if that happened."

When asked on Thursday if he was concerned by the votes in Knesset, Trump told reporters, "Don't worry about the West Bank. Israel's not going to do anything with the West Bank."

Israeli lawmakers on Wednesday advanced two bills paving the way for the annexation, leading to condemnation on Thursday from US Vice-President JD Vance, who was in Israel at the time and who echoed Trump's comments.

As he ended his trip, Vance hit out at the votes in Israel's parliament in favor of examining the two bills, which means they will be brought forward for further readings.

"If it was a political stunt, then it was a very stupid one and I personally take some insult to it," he said. "The West Bank is not going to be annexed by Israel. The policy of the Trump administration is that the West Bank will not be annexed by Israel, that will continue to be our policy."

In a joint statement carried by Saudi state media on Thursday, more than a dozen states, including Saudi Arabia, Indonesia, Qatar, Jordan and Turkiye, condemned the Israeli vote.

They said the move constitutes a flagrant violation of international law and United Nations Security Council resolutions, particularly Resolution 2334, which condemns all Israeli measures aimed at altering the demographic composition, character and legal status of the occupied Palestinian territories since 1967.

The Israeli government seemed "flabbergasted", commented Al Jazeera, as Ofir Katz, chairman of the government coalition, said in a statement that the bills for the full annexation of the West Bank and the annexation of the large-scale settlement of Maale Adumim near Jerusalem will not be advanced until further notice.

However, observers said de facto annexation is slowly taking place as more than 700,000 Israelis live in illegal settlements in the West Bank and occupied East Jerusalem.

The US remains Israel's most important military and diplomatic supporter. The US has provided Israel with billions of dollars in military assistance in the Gaza conflict, along with unwavering diplomatic support.

Israeli Prime Minister Benjamin Netanyahu's Likud party boycotted and criticized the votes, though members of his ruling coalition support annexation.

US Secretary of State Marco Rubio is to meet Netanyahu later Thursday "to support the successful implementation of President Trump's Comprehensive Plan to End the Conflict in Gaza", according to the US State Department. Before taking off for Israel on Wednesday, he told the media that there is potential for the Knesset bid to be "threatening to the peace deal".

Yousef Munayyer, a senior fellow at the Arab Center Washington DC, said Trump's comments on the prospect of Israel annexing the West Bank were striking in the context of decades of unequivocal US support for Israel.

"I'm not sure any American president has ever laid down such a clear red line relating to an Israeli action," he wrote on social media. "And it could all be bluster. But for an American president to utter the words 'Israel would lose all of its support from the United States' was previously thought to be sacrilege."

Meanwhile, delegations from Hamas and its longtime rival Fatah met in Cairo on Thursday to discuss the second phase of the US-backed Gaza ceasefire plan, Egypt's state-linked Al-Qahera News reported.

Agencies contributed to this story.