The Tokyo Metropolitan Police Department is stepping up measures to prevent assaults by lone offenders who act without connections to organizations.

The move comes after former Prime Minister Abe Shinzo was fatally shot by a man in the western city of Nara in July last year and a man threw an explosive device in the vicinity of Prime Minister Kishida Fumio in Wakayama, another city of western Japan in April.

The Tokyo police department believes that cooperation from citizens is indispensable to prevent attacks by recognizing their warning signs in advance.

On Tuesday, police officials attended a meeting of real estate firms in Tachikawa City.

The officials said the smell of gunpowder, sounds of metal processing, or many bottles of chemicals left at a garbage collection point suggest the possibility that a gun or an explosive device is being made.

The officials handed out flyers asking people to report any suspicious signs to police.