US President Donald Trump’s Dec. 6 proclamation on Jerusalem appears to have complicated efforts to restore Jordan-Israel ties. The two countries have been embroiled in conflicts over repeated incursions on Haram al-Sharif (which Israel calls the Temple Mount) by Jewish settlers and the July 23 killing by a guard of two Jordanian citizens at the Israeli Embassy in Amman. Since then, Amman has refused to allow the Israeli ambassador and embassy staff to return to the kingdom until the assailant is put on trial and families of the victims are compensated. The row has threatened work on a regional water and energy project linking the Red Sea to the Dead Sea, an undertaking of high strategic importance to Jordan.

But Trump’s decision to recognize Jerusalem as Israel’s capital and to move the American embassy there has added a new twist to the strained relations between the two neighbors who signed a peace treaty in 1994. Encouraged by the government, tens of thousands of Jordanians have been protesting the US move following Friday prayers in Amman and other major cities across the kingdom. Enraged protesters have called on their government to abrogate the 23-year-old peace treaty and all bilateral agreements with “the Zionist entity.” Enmity toward Israel has reached new heights as Jordanians expressed solidarity with Palestinians in the occupied territories who have been clashing with Israeli soldiers almost every day since the Trump announcement.

Public outrage coincided with an extraordinary diplomatic offensive by King Abdullah aimed at rallying international support against the US move, which he had described as dangerous and a violation of international law. Jordan’s campaign had focused on the European Union, the Vatican, the Arab League and the Organization of Islamic Cooperation. Amman’s coordination with the EU had thwarted an attempt by Israeli Prime Minister Benjamin Netanyahu to convince European countries to support the US decision during a surprise visit to Brussels on Dec. 11.

Jordan has argued that the fate of Jerusalem, in particular occupied East Jerusalem, should be decided in final status negotiations between Israel and the Palestinians. Trump’s vague pronouncement is seen as pre-judging the city’s future, threatening Jordan’s special role as custodian of Muslim and Christian holy sites in the Old City and destroying the two-state solution. Furthermore, it pre-empts credible negotiations to reach a peaceful settlement and strengthens the Israeli far-right's false claims that a Palestinian state already exists in Jordan. Far worse, the decision resurrects Jordanian fears of a possible transfer of Palestinians by Israel to the east bank of the Jordan River, a scenario that undermines the Hashemite kingdom.