Direct quote 1999
“I've heard the American military is using video games as training tools now too, making their soldiers play DOOM. Apparently people are more willing to pull a trigger on the battlefield if they've played these games. Of course, this leads to the impression that "games are training for murderers!"”
What it documents
In 1999 Kojima said he had long been accused of making violent games, and that just when the Columbine massacre in Colorado occurred, shortly after there was an E3 and he heard a lot of criticism. He added that the US military was already using video games as training tools, making their soldiers play DOOM because, he said, people become more willing to pull a trigger on the battlefield if they have played those games, which fosters the impression that games are training murderers.
Source
shmuplations.com; Kojima × Tsukamoto conversation in Game Hihyou magazine (1999), unofficial English translation. View source ↗
“Right around when the Columbine shooting took place in Colorado, shortly after there was an E3 event, and I heard a lot of criticism then.”