Far-fetched as Mr. Trump’s vision for Gaza may be — the Arab world has roundly rejected it and any forcible removal of a population violates international law — it abruptly shifted attention away from the future of the cease-fire deal, whose initial, six-week phase is due to end in early March.

Whatever becomes of President Trump’s proposal to take over Gaza and resettle the Palestinians there, the Arab world is not on board. Many consider the plan a form of what the U.N. terms “ethnic cleansing.