Donald Trump reportedly told the Emperor of Japan that mass shootings can occur "anywhere", despite the country having some of the world's most stringent gun control policies.
The US President met Emperor Akihito and Empress Michiko before a round of talks with Japan's prime minister, Shinzo Abe, on Monday.
When the emperor brought up Sunday's mass killing at a church in Texas, Mr Trump called it a "terrible incident" and said the killings "can happen anywhere", according to the Mainichi Shimbun.
A lone gunman killed 26 people at First Baptist Church in Sutherland Springs, the worst such massacre by a lone gunman in Texas and one of the five most lethal in modern US history.
It came a little over a month after another lone shooter killed 58 people and injured hundreds more in Las Vegas.
But in Japan, gun deaths are measured in single figures annually, compared to tens of thousands in the US.
Handguns are banned and anyone seeking a licence for a shotgun or air rifle must undergo a string of background checks, a written test and health evaluations.
Even police rarely use their sidearms and must attain a black belt in judo or other Japanese martial art before qualifying.
Journalist Anthony Berteaux told the BBC earlier this year: "What most Japanese police will do is get huge futons and essentially roll up a person who is being violent or drunk into a little burrito and carry them back to the station to calm them down."