"Circumstances are changing," one official said, and they should "get on board before events overtake them."
US diplomats raised a toast to their last day in the old US embassy in Israel, long based in Tel Aviv. The opening event on Monday will be attended by hundreds of guests, including the US ambassador to Israel, David Friedman; the daughter and son-in-law to the president, Ivanka Trump and Jared Kushner; Treasury Secretary Steve Mnuchin; and Jason Greenblatt, the US special representative for international negotiations.
Trump will not attend the opening but will instead offer remarks by video. Vice President Mike Pence will address a gathering in Washington that evening marking the 70th anniversary of Israel's independence.
The officials noted their decision to open the Jerusalem embassy has had no tangible effect on their relations with other countries– nor has it changed the course of an historic alignment between Israel and the Arab world.
In particular, one official lauded a message from a Bahraini official on Thursday defending Israel's response to an Iranian rocket barrage into the Golan Heights this week.
"It's a sea change we've been waiting for," the official said. "It's so important to see an Arab nation recognize Israel as a country, and a country that has a right to defend itself."