The U.K. government on Thursday said that the country is facing an antisemitism emergency and pledged to increase security for Jewish communities after a string of arson attacks and a double stabbing that have sparked fear and anger among Jews. The country’s official threat level from terrorism was raised from substantial to severe after Wednesday’s stabbing attack in London, which police have called an act of terrorism. Severe is the second-highest rung on a five-point scale and means intelligence agencies consider an attack highly likely in the next six months.Prime Minister Keir Starmer said that his government “will do everything in our power to stamp...