LONDON — "I am not afraid of Bibi (Netanyahu). I will not be anybody's fig leaf," said Ehud Barak, leader of Israel's Labor Party, defending his decision to join the hard-right coalition government formed by Likud leader Benjamin Netanyahu. But off in the distance there was a curious whirring noise.

The sound was identified by Ophir Pines-Paz, a prominent Knesset member who is on the left of the Labor Party: "Yitzhak Rabin, Golda Meir and Moshe Sharett (all former Labor prime ministers) are turning over in their graves." In fact, they are spinning at high speed, for Barak has abandoned Labor's traditional values to save its electoral prospects.

The coalition he has joined committed to expanding the...