The Bush administration was busy Thursday defending its understandings with Israeli Prime Minister Ariel Sharon on the shape of a future Israeli-Palestinian peace accord. Secretary of State Colin Powell said the agreements only reflect long-standing realities, and will kick-start the regional peace process by securing an Israeli withdrawal from Gaza and parts of the West Bank.

The agreements, included in a statement by President Bush and his exchange of letters with Mr. Sharon, drew almost universal criticism from the Palestinians and Arab governments.

But administration officials are urging a closer look at the documents, which they say prejudge no issues in final-status negotiations, yet will also almost certainly lead to the first Israeli withdrawals from settlements in Palestinian areas more than three decades.

Most controversial of the language in Wednesday's White House agreements was a statement by Mr. Bush that it is "unrealistic" to expect that final-status talks will lead to a full and complete Israeli return to its pre-1967 boundaries. He also said Palestinian refugees should eventually be settled in an envisaged Palestinian state rather than Israel.

At an impromptu news conference here, Secretary of State Colin Powell said the agreements will open the way for Mr. Sharon to implement his plan of "disengagement" from the Palestinians that is to include the removal of all Israeli settlements from Gaza and four geographically-remote ones in the West Bank.

He said it is the beginning of process and not the end of one, and insisted the understandings have not cost the United States its role as an "honest broker" in peace efforts. He said in his comments Wednesday, President Bush was only recognizing realities that already exist on the ground.

"One has to do with the right of return and where should the return actually be to," he said. "And with the presence of a Palestinian state living side by side in peace with Israel, it seems logical to believe that that is where the return should take place as opposed to Israel. But this is something for the two sides to negotiate with each other as they move ahead."

On the territorial issue, Mr. Powell said the President was recognizing what Israel and Palestinian negotiators have already accepted in principle in past rounds of peace talks, that there will have to be territorial adjustments in reaching a two-state settlement of the conflict.

"The changes in demographics and population centers, changes that have occurred in both sides, have led previous negotiating teams to the conclusion that modifications, adjustments, changes will be required to the armistice lines," he said. "Everybody knows this. So rather than deny this reality, let's talk about this reality and let the two sides in the process of their negotiations, and in trying to achieve final status between them determine what is appropriate."

Mr. Powell said it is time now for Israel to begin removing the settlements, and for the Palestinians to crack down on terrorism, in order to get on with the negotiating process called for in the international "road map" to peace.

The Secretary spoke with Egyptian Foreign Minister Ahmed Maher Thursday as he continued telephone diplomacy with Arab leaders on the U.S.-Israeli understandings. Jordan's King Abdullah and Palestinian Foreign Minister Nabil Shaath are due in Washington for talks next week, and U.S. officials said there is no indication that either will change his plans despite criticism of the agreements.