(JTA) – Jordan’s government spokesman warned of “catastrophic” repercussions if President-elect Donald Trump moves the U.S. Embassy in Israel to Jerusalem as he indicated he would. Such a move could affect relations between the United States and regional allies, including Jordan, Information Minister Mohammed Momani told The Associated Press on Jan. 5. An embassy move would be a “red line” for Jordan, would “inflame the Islamic and Arab streets” and serve as a “gift to extremists,” Momani said, adding that Jordan would use all possible political and diplomatic means in a bid to prevent such a decision.

Jordan, a key U.S. ally in the Middle East, is the custodian of Islam’s third holiest shrine, the Al-Aqsa mosque, in eastern Jerusalem. Israel captured eastern Jerusalem from Jordan in 1967 and annexed it to its capital. The Palestinians want to establish the capital of a future state in Jerusalem. Much of the world has not recognized Israel’s annexation of eastern Jerusalem and most countries, including the United States, maintain their embassies in Tel Aviv.

Trump said during the presidential campaign that he intended to move the U.S. Embassy to Jerusalem. Last month, Trump adviser Kellyanne Conway was quoted as saying that moving the embassy to Jerusalem is a “very big priority” for the president-elect. Trump’s choice for U.S. ambassador in Israel, David Friedman, has said he looks forward to working from Jerusalem.