One of our favorite anecdotes about Prime Minister Sharon comes from a visit to his farm years ago. A visitor turned to his host and said he was surprised that Mr. Sharon did not have more fences. Mr. Sharon chuckled and said, “I like to make the other guy build the fences.”

It’s a story that came to mind last night with the news that, during a meeting with Mr. Sharon yesterday, President Bush’s national security adviser, Condoleezza Rice, objected to Israel’s building of fences to prevent terrorist attacks by Palestinian Arabs from the West Bank.

According to a report by Herb Keinon in the Jerusalem Post,” Rice, during a meeting with Prime Minister Ariel Sharon and the inner cabinet, expressed U.S. concern that the fence was creating facts on the ground that would prejudge a final settlement, and indicated the U.S. would like to see construction stopped as a confidence-building measure.”

The Jerusalem Post report went on: “Sharon, however, replied that if the choice was between having a disagreement with the U.S. over the fence, or burying Israeli victims of suicide bombers, it is clear what choice Israel would make.”

The apparent shift in Mr. Sharon’s attitude toward fences is telling about more than the former general’s mellowing over the years. It underscores the fundamental asymmetry between Israel’s position and that of the Palestinian Arabs. The Palestinian Arabs are not trying to build a fence to protect themselves against suicide bombing attacks by Israelis on Palestinian Arab civilians. There are no such attacks. This is an asymmetry of which the American government mediators sometimes seem will fully ignorant.

Yesterday, a White House spokeswoman, Ashley Snee, in response to the offer by Hamas and Islamic Jihad of “suspension of the military operations against the Zionist enemy for three months,” told reporters, “Anything that reduces violence is a step in the right direction…Under the road map, parties have an obligation to dismantle terrorist infrastructure. There is still more work to be done.”

Ms. Snee’s interpretation notwithstanding, under the road map, “parties” do not have an obligation to dismantle terrorist infrastructure. One party does: The Palestinian Arabs. The Israelis do not have a terrorist infrastructure. The Palestinian Arabs do. The White House isn’t doing Israel, the cause of peace, or the war on terrorism any favors by fudging the matter, much less by pressing Israel to refrain from the fence-building effort — arrived at by a free, democratic process — that Mr. Sharon is undertaking to defend Israeli citizens from Arab aggression.