Israel is stepping up its attacks on the Obama administration, saying it has proof from Arab sources that the U.S. actively helped craft a U.N. resolution that declared Israeli settlements illegal.

David Keyes, a spokesman for Prime Minister Benjamin Netanyahu, says Israel has “ironclad information” that the White House helped draft the language of the resolution. Citing Arab sources, he said Tuesday that the White House “pushed hard” for its passage.

Israel is livid about the resolution, which gave the Palestinians a major diplomatic victory.

The United States broke with past practice and allowed the Security Council to condemn Israeli settlements in the West Bank and east Jerusalem as a “flagrant violation” of international law.

“The decision lays the foundation for any future serious negotiation … and it paves the way for the international peace conference slated to be held in Paris next month,” Palestinian President Mahmoud Abbas said early Tuesday in his first public remarks since the U.N. vote.

“We hope this conference comes up with a mechanism and timetable to end the occupation,” Abbas told a meeting of his Fatah party. “The (resolution) proves that the world rejects the settlements, as they are illegal.”

On Jan. 15, days before President Barack Obama leaves office, France is expected to host a conference where dozens of countries may endorse an international framework for peace between Israel and the Palestinians. Israeli Prime Minister Benjamin Netanyahu vehemently opposes such a move, saying it would undermine the negotiating process.

Netanyahu has repeatedly called on Abbas to meet for direct talks without preconditions. Abbas has refused unless Israel first ends settlement construction.

The Palestinians claim the West Bank, along with east Jerusalem, home to holy sites sacred to Jews, Muslims and Christians, as parts of their future state. Israel says settlements, along with other core issues like security, should be agreed upon in direct talks.

Keyes says Israel will not join the conference.

Days after the United Nations voted to condemn Israeli settlements in the West Bank and east Jerusalem, Donald Trump questioned its effectiveness Monday, saying it’s just a club for people to “have a good time.”

As to the U.N., things will be different after Jan. 20th.

— Donald J. Trump (@realDonaldTrump) December 23, 2016

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!

— Donald J. Trump (@realDonaldTrump) December 26, 2016

This story is by The Associated Press.