JERUSALEM (JTA) — Any unilateral Israeli action toward annexing West Bank territory could endanger the Trump administration’s peace plan, U.S. Ambassador to Israel David Friedman warned in a two-part tweet Sunday.

Friedman wrote that the United States needs to approve any annexation plans before Israel takes action.

President Trump’s Vision for Peace is the product of more than three years of close consultations among the President, PM Netanyahu and their respective senior staff. As we have stated, the application of Israeli law to the territory which the Plan provides to be part of

— David M. Friedman (@USAmbIsrael) February 9, 2020

Israel is subject to the completion a mapping process by a joint Israeli-American committee. Any unilateral action in advance of the completion of the committee process endangers the Plan & American recognition.

— David M. Friedman (@USAmbIsrael) February 9, 2020

Friedman’s tweets came hours after Israeli Prime Minister Benjamin Netanyahu announced Israel had begun taking steps toward annexation.

“We are already at the height of the process of mapping the area that, according to the Trump plan, will become part of the State of Israel,” Netanyahu said at a campaign event Saturday night in Ma’ale Adumim, a West Bank city near Jerusalem that would be annexed under Trump’s plan. “It won’t take too long.”

Friedman’s tweet also signaled a complete reversal of the ambassador’s earlier support for immediate annexation of the West Bank and Jordan Valley. He had told reporters at the White House immediately after the announcement that Israel could, in his view, “annex settlements at any time” and that the country “should not wait at all” to do so.

He began walking those comments back the following day, saying it is a “process that requires some effort,” and that Israel would first need to present detailed maps before the United States would approve such a move. Jared Kushner, President Donald Trump’s son-in-law and the plan’s architect, has said Israel should wait until after next month’s elections before taking action.

Under the plan, the United States would approve of Israel annexing about 30 percent of the West Bank, including all of the Jewish settlements and the Jordan Valley.