Calls for direct action are based on the arguments that negotiations are no longer feasible because of enduring political divisions on both sides and the changing dynamics inspired by the Arab Spring, which demand that leaders take more populist positions in line with anti-Israel public sentiment. But some advocates of this approach have also said that they believe the door should remain open to negotiations, suggesting that unilateral steps could be phased in over many years and be designed, in part, to give Israel a stronger hand in final status talks.

The Palestinian Authority has opposed any effort by Israel to decree the contours of its territory and abandon a negotiated settlement on a wide variety of issues, including the future of Jerusalem. The Palestinian Authority, however, did take its own unilateral steps last fall, when it pursued United Nations recognition, something it is considering doing again. Israel has criticized such efforts for stepping outside the bounds of negotiations. The Obama administration has strongly opposed unilateral action by either side, and some senior Israeli officials have worried that such a move by Israel could provoke an uprising by Palestinians.

“The core issues of the conflict can only be resolved by direct negotiations,” Daniel B. Shapiro, the United States ambassador to Israel, said Wednesday. Nabil Abu Rudaineh, a spokesman for the Palestinian Authority, also objected to the call for unilateralism, saying, “This policy won’t lead to a solution and would prolong the conflict. It will end the idea of the two-state solution.”

Both Mr. Barak and Prime Minister Benjamin Netanyahu said at the security conference that they, too, preferred a final-status solution of two states for two peoples, and that the broad unity government they formed this month presented a unique opportunity for a peace deal. But many here see bilateral negotiations as all but impossible and are seeking a new paradigm.

Mr. Barak, who briefly spoke about the Palestinian conflict at the end of a wide-ranging lecture, did not offer any specifics by design, according to a senior aide who said later that “what he’s talking about is the importance of taking action.”