An officer with Washington's Metropolitan Police Department came under an unprovoked attack Friday from a man wielding an ax, police said, the second such attack in two weeks that is prompting warnings and new protocols to officers on the job. The attack, and another last week in which a man attacked four New York City officers with a hatchet in Queens, prompted an immediate increase in security for officers in both D.C. and New York. The New York Police Department said in a memo: "Police Officers on patrol should maintain a heightened level of awareness." The attack in Washington occurred...