President Trump's decision not to immediately move the U.S. embassy in Israel to Jerusalem is "deeply disappointing," a House Republican lawmaker said Thursday.

"Israel is the only nation in the world where an American embassy is not located in its chosen capital city," said Florida Rep. Ron DeSantis, a founding member of the conservative House Freedom Caucus. "It is long past time that we rectify this error and locate our embassy in Jerusalem and it is deeply disappointing that the president has decided not to do so."

Trump promised to relocate the U.S. embassy from Tel Aviv to Jerusalem, a move that would have angered the Arab world by signaling American support for the idea of Jerusalem as Israel's capital. Israel captured East Jerusalem in the 1967 war, when Arab armies mobilizing against the Israelis were defeated by a surprise pre-emptive strike. The Palestinian Authority wants East Jerusalem as the capital of a future Palestinian state, so the status of Jerusalem has remained contested in diplomatic circles despite the military victory.

An act of Congress called for the relocation of the U.S. embassy during Bill Clinton's presidency, but every president since that law's passage has invoked a waiver authorized by the law to delay the move. The White House said waiving it would boost the prospects of a peace deal, which Trump has also been seeking.

"President Trump made this decision to maximize the chances of successfully negotiating a deal between Israel and the Palestinians, fulfilling his solemn obligation to defend America's national security interests," White House press secretary Sean Spicer said Thursday. "But, as he has repeatedly stated his intention to move the embassy, the question is not if that move happens, but only when."

An American diplomat who served in the Obama administration thinks that move could come as early as this year, if the peace talks are properly executed. "[Trump] will never have more leverage than he has now to get hard decisions out of all of them," Daniel Shapiro, U.S. ambassador to Israel from 2011 to 2017, tweeted.

For Israel, that means "clear steps" toward a two-state solution that would probably require Israeli Prime Minister Benjamin Netanyahu to lose some allies and gain others in order to maintain a majority coalition, Shapiro suggested. Palestinians should be required to "end payments to terrorists," as American lawmakers have demanded. Finally, Arab states that refuse to recognize Israel — Saudi Arabia is the most prominent — would have to "begin normalizing" relations with Israel.

"In that context & with proper planning and budgeting, [Trump] can inform all sides well in advance: no more waivers," Shapiro suggested in ensuing tweets. "No surprises to any side. Then establish the embassy in [west] Jerusalem. Shatter [the Palestinian] myth that Israel has no Jerusalem claims & treat Jerusalem as the capital it is. Also make clear that [East] Jerusalem has a different status, needs to be negotiated & [Palestinians] will need their capital in its Arab neighborhoods.

DeSantis thinks that Trump should have kept his promise, particularly in light of Israel's human rights record. "Israel's stewardship of Jerusalem has been tremendous and has included guaranteeing religious freedom for Christians and Muslims as well as Jews — something that was nonexistent during the city's Arab occupation," he said.