The United Arab Emirates and Bahrain on Tuesday will become the latest Arab states to break a longstanding taboo when they sign agreements toward normalising relations with Israel in a strategic realignment of West Asian countries against Iran.

U.S. President Donald Trump was due to host the White House ceremony around noon, capping a dramatic month when first the UAE and then Bahrain agreed to reverse decades of ill will without a resolution of Israel’s decades-old dispute with the Palestinians.

At the U.S.-brokered event, Israeli Prime Minister Benjamin Netanyahu will sign agreements with Emirati Foreign Minister Sheikh Abdullah bin Zayed al-Nahyan and Bahraini Foreign Minister Abdullatif Al Zayani.

The deals make them the third and fourth Arab states to take such steps to normalise ties since Israel signed peace treaties with Egypt in 1979 and Jordan in 1994.

The UAE’s Minister of State for Foreign Affairs, Anwar Gargash, said on Tuesday his country’s decision to normalise relations with Israel had “broken the psychological barrier” and was “the way forward” for the region, creating more leverage.

The back-to-back agreements, which have drawn bitter condemnation from the Palestinians, mark an improbable diplomatic victory for Mr. Trump. He has spent his presidency forecasting deals on such intractable problems as North Korea’s nuclear programme only to find actual achievements elusive.

Bringing Israel, the UAE and Bahrain together reflects their shared concern about Iran’s rising influence in the region and development of ballistic missiles. Iran has been critical of both deals.

With Mr. Trump up for re-election on November 3, the accords could help shore up support among pro-Israel Christian evangelical voters, an important part of his political base.

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Speaking to Fox News hours before the ceremony, Mr. Trump said he expected more Arab countries to normalise ties with Israel and predicted the Palestinians would eventually join as well or else be “left out in the cold”.

One target of White House appeals is Saudi Arabia, the biggest Gulf Arab power. So far the Saudis, whose King is custodian of Islam's holiest sites and rules the world's largest oil exporter, have signalled they are not ready.