"Measures have already been taken to increase security for leaders at the Hiroshima summit after the assassination of former Prime Minister Shinzo Abe. But after Saturday's incident, the number of security guards and police officers responsible for the safety of leaders and guests is likely to be increased," Osanai said.
He added that the Wakayama incident was the first time explosives had been used in an attempted attack on a high-ranking official.
"Algorithms for action in such cases have existed before, but they are likely to be adjusted and specified after this incident. Also in connection with this incident, the security arrangements for the G7 leaders are likely to be revised and supplemented," Osanai said.
On Saturday, as Kishida was touring a venue ahead of a stump speech in the prefecture of Wakayama, a young man from the crowd threw a cylindrical object toward him, which was followed by the sound of an explosion and the smell of smoke. The prime minister was unharmed and immediately left by car.
Two cylindrical objects were later recovered from the scene, one of which had exploded and the other was being held by the assailant, Japanese media reported. The perpetrator was identified as a 24-year-old man from Hyogo Prefecture.
The incident is not the first attack on a Japanese politician in the country. Less than a year ago, on July 8, 2022, Abe was fatally shot while speaking during his campaign speech in Nara Prefecture. His assassin, Tetsuya Yamagami, approached the politician from behind and fired two shots from a distance of about 33 feet. The attacker told investigators that he had decided to carry out the assassination because of Abe's alleged ties to a religious sect that he claimed had bankrupted his mother. The group has denied having had anything to do with the former prime minister.
Japan is the G7's char country in 2023 and will be host the annual top-level summit in Hiroshima from May 19-21.