U.S.-Israel relations suffered a significant setback after the United States abstained last week in a 14-0 U.N. Security Council vote that condemned Israeli settlements in the West Bank and East Jerusalem. Israeli Prime Minister Benjamin Netanyahu summoned the U.S. ambassador to Israel to directly express his displeasure, and on Tuesday Israeli officials claimed to have “ironclad” information that the Obama administration didn’t just abstain, but actively helped develop the resolution.

President-elect Donald Trump, who urged President Obama to veto the measure, tweeted after the vote that, “As to the U.N., things will be different after Jan. 20th.”

And indeed they will, as the incoming Trump administration vows to have much better relations with Netanyahu than Obama has experienced.

But Trump should recognize that the U.S.-Israel alliance does not mean a blank check for policies that preclude a two-state solution to the seemingly eternal Israel-Palestine issue. In fact, Trump has an opportunity unique to incoming presidents: As a perceived preferred alternative to Obama and Hillary Clinton, he can press Israel toward a lasting agreement rather than regress toward the one-state status preferred by right-wing members of Netanyahu’s governing coalition.

Already those voices are amplified: Defiantly, the Israeli government on Monday indicated it would approve 600 additional housing units in East Jerusalem as part of a broader plan of up to 5,600 new homes.

Such a move might mollify the settler movement and its supporters in Israel. But it’s likely to further deteriorate relations with the Palestinian Authority, and test relations with governments worldwide that believe they must diplomatically react to expanding settlements. These voices matter, despite Trump’s denigrating the U.N. in (again) a tweet that read: “The United Nations has such great potential but right now it is just a club for people to get together, talk and have a good time. So sad!”

The U.N. is, of course, much more than that, and resolutions can damage Israel’s diplomatic and even legal standing on the Palestinian issue. Trump had an encouraging message in the wake of his election, telling the Wall Street Journal that he would like to make “the ultimate deal” between Israel and Palestine “for humanity’s sake.”

But negotiating such a deal will be much more difficult if Trump wavers on the two-state policy. So it’s worrisome that he nominated David Friedman, a bankruptcy lawyer with no diplomatic experience, to be ambassador to Israel. Friedman has spoken against the two-state solution, has supported the kind of settlements at issue at the U.N., and has slandered the president by accusing Obama of “blatant anti-Semitism.”

Trump’s stalwart support of Israel’s government puts him in a position to prod its leaders toward the necessary concessions for an accord. The deeply divided Palestinians must prove that they are up to the responsibilities of peace, too. Trump can and should be a true friend to Israel by prioritizing a durable diplomatic agreement with Palestine.