YOKOSUKA NAVAL BASE, Japan — U.S. and Japanese security guards apprehended a Japanese man Saturday after he charged into Yokosuka Naval Base with a kitchen knife.

Hisashi Ishii, a 31-year-old from Yokohama, rushed through Yokosuka’s Carney (main) Gate around 1:30 p.m. carrying a knife with a blade about 6.3 inches long, a Yokosuka Police spokesman said Tuesday. Japanese law prohibits carrying knives with blades longer than about 2.3 inches.

Ishii made it 150 feet inside the gate before being taken down by Japanese riot police, the spokesman said.

There was more security than normal in the area at the time, said base spokesman Phil Molter, because extra guards were on hand to prepare for a planned 3,000-person protest of the U.S. Navy plan to bring a nuclear–powered aircraft carrier to Yokosuka.

Demonstrators began the rally in nearby Verny Park, then marched and shouted slogans outside the base gate Saturday afternoon.

The extra Japanese police on hand “assisted in the apprehension” of the person with the knife, Molter said, adding that “CFAY security guards man the gate normally and the Japanese police stand watch outside the gate.”

Base officials did not comment on the reasons for Ishii’s actions. The Yokosuka Police spokesman said that the man was trying to get the guards to shoot him.

Ishii told the police he wanted to commit suicide but couldn’t. He decided that if he ran into the base, he would be killed, said the spokesman, adding that Ishii has a history of mental illness.

He was arrested on suspicion of violating swords and firearms control laws and entering the base without permission. He was taken into police custody and remained there Tuesday. The case was sent to the prosecutor’s office in Yokosuka on Monday, the spokesman said.