A bulletin sent by federal authorities Saturday instructed law enforcement officials to watch for signs of a possible “lone wolf” attack inside the U.S. in retaliation for the killings of two key American members of al-Qaida. There was no current intelligence about an imminent attack, the notice said.

 But police were told to watch for suspicious behavior. In particular, the bulletin said that would-be attackers could follow plans found in Samir Khan’s English-language magazine, Inspire.

 Seven issues of the magazine were distributed over the Internet in the last year. The publication encourages readers to launch attacks that don’t require a large network of operatives.

Tribune Washington bureau