JERUSALEM  In a blunt and belligerent speech on his first day as Israel’s new foreign minister, the hawkish nationalist Avigdor Lieberman declared Wednesday that “those who wish for peace should prepare for war” and that Israel was not obligated by understandings on the Israeli-Palestinian conflict reached at an American-sponsored peace conference in late 2007.

“Those who think that through concessions they will gain respect and peace are wrong,” Mr. Lieberman said during a transfer ceremony at the Foreign Ministry. “It is the other way around; it will lead to more wars.”

His predecessor in the post of foreign minister, Tzipi Livni, a centrist, led Israel’s negotiating team with the Palestinians in a year of intensive talks after the 2007 conference, held in Annapolis, Md.

The aim of the Annapolis process, as it became known, was to agree on the framework for a Palestinian state alongside Israel by the end of 2008, a goal that was not achieved.