On Dec. 21, amid his morning workout, an afternoon round of golf and a family dinner with friends, President Obama interrupted his Hawaii vacation to consult by phone with his top national security team in Washington. Egypt had introduced a resolution at the U.N. Security Council condemning Israeli settlements as illegal, and a vote was scheduled for the next day. The idea had been circulating at the council for months, but the abrupt timing was a surprise. Obama was open to abstaining, he said on the call, provided the measure was “balanced” in its censure of terrorism and Palestinian violence...