A group of former top military commanders in NATO countries including the U.S. are calling on their governments to insist on the right to preemptive nuclear attack. In a new manifesto, the former army leaders — including ex-joint chiefs of staff chair, General John Shalikashvili — say NATO should maintain that a “first strike” nuclear option remains an “indispensable instrument.” The group says this is in part because there is “simply no realistic prospect of a nuclear-free world.” The proposal is likely to be reviewed at a NATO summit in April.