Prince Turki al-Saud was apparently responding to U.S. President Donald Trump who said on Wednesday he expected Saudi Arabia to join a deal announced last week by Israel and the United Arab Emirates to normalise diplomatic ties.

The UAE is only the third Arab state in more than 70 years to forge full relations with Israel. Under the U.S.-brokered deal, Israel shelved plans to annex settlements in the occupied West Bank, which Palestinians seek as part of a future state.

The UAE said Israel’s commitment had kept alive the possibility of a two-state solution to the Israeli-Palestinian conflict.

Israel hitherto had no formal ties with Gulf Arab states but shared concerns with the UAE about Iran’s regional influence and actions, along with the UAE’s role as a regional business hub, led to a limited thaw and discreet contacts in recent years.

The deal raised speculation that other U.S.-backed Gulf Arab countries might follow. But Prince Turki said Saudi Arabia, the biggest Gulf Arab power which has traditionally guided policy towards Israel, expected a higher return from Israel.

“Any Arab state that is considering following the UAE should demand in return a price, and it should be an expensive price,” he wrote in the Saudi newspaper Asharq al-Awsat.

“The Kingdom of Saudi Arabia has set a price for concluding peace between Israel and the Arabs – it is the creation of a sovereign Palestinian state with Jerusalem as capital, as provided for by the initiative of the late King Abdullah.”

That 2002 Arab League plan offered Israel normalised ties in return for Israeli withdrawal from all territories – the West Bank, Gaza and East Jerusalem – captured in the 1967 Middle East war, and a Palestinian state there.

But Prince Turki also voiced understanding for the UAE’s decision, noting that Riyadh’s close ally had secured a key condition – a halt to Israeli annexation plans.

In the first Saudi reaction to the UAE-Israeli deal, Foreign Minister Faisal bin Farhan said on Wednesday Riyadh remained committed to the Arab peace initiative.

Prince Turki, a former ambassador to Washington and ex-intelligence chief, holds no government office now but remains influential as current chairman of the King Faisal Center for Research and Islamic Studies.