Barbara Tuchman, in her classic book “March of Folly,” examined four cases in history when governments acted contrary to their own best interests: the Trojans who let the Greeks bring the fatal horse into their midst; the papacy, which allowed and even brought about the Protestant secession; the British who lost America, and America, which lost the war in Vietnam.

When I heard that during Vice President Joseph Biden’s visit to Israel the government had approved the construction of 1,600 new homes in East Jerusalem, I was reminded of Tuchman’s book.

Beside the blunder of rubbing it in the face of your best friend and ally, there lies a much more substantial error: By expanding settlements instead of separating from the Palestinians while we still can, we Israelis are dooming ourselves to lose the Jewish and democratic state that has been won with so much sacrifice. In other words, we are immersed in our own march of folly. And we are doing it with our eyes open.

Ehud Barak, Israel’s defense minister, should know. More than 20 years ago, when he was a general in uniform and I was the head of the Israeli Defense Forces’ publishing house, he urged me to translate military history books. “We need to learn from history,” he told me.