UNITED NATIONS (AP) — A key architect of the long-awaited U.S. plan for Israeli-Palestinian peace warned Wednesday that "nothing can be meaningfully fixed" until Gaza's Hamas rulers and Palestinian Islamic Jihad renounce their vows to destroy Israel and stop carrying out violent acts.

In a wide-ranging speech at the Security Council's monthly Mideast meeting, Jason Greenblatt also said the Palestinians should attend a workshop next month where the U.S. will roll out its economic plan "that can pave the way for Palestinian prosperity." The Palestinian Authority has said it will not attend.

Gree...