A former Sumitomo Corp employee appeared in court Wednesday for his first trial regarding repeated illegal entries into the U.S. Navy’s Yokosuka base.

The case highlights potential security vulnerabilities at a critical military installation in Japan, as the defendant reportedly bypassed security measures multiple times without detection.

Kei-taka Mizuno, aged 45 to 46 [1, 2], is accused of entering the base about 30 times [1]. During the hearing on May 13, prosecutors sought a prison sentence of 10 months [1]. The prosecution said the intrusions were bold and malicious, noting that Mizuno even brought his wife and pet dog into the facility [1].

Defense counsel said Mizuno had a strong admiration for the U.S. military, which began when he aimed to become a U.S. service member as an elementary school student and underwent rigorous training. The counsel said that Mizuno is reflecting on his actions and said he will not repeat the offense [1].

While the defendant cited personal admiration for the military as his motivation, officials have questioned the ease of the breaches. A public safety official said the methods used to enter the base were crude [2].

The court proceedings focus on the frequency of the unauthorized entries and the nature of the security failures that allowed a civilian to repeatedly access a restricted military site. The prosecution said that the inclusion of family members, and pets, during these incursions underscores a disregard for the law and military security protocols [1].

“Prosecutors seek a 10-month prison term for a man who allegedly entered the Yokosuka base about 30 times.”

This trial underscores a significant lapse in perimeter security at the Yokosuka base, where a civilian was able to enter dozens of times. The fact that the intrusions were described as 'crude' suggests that the breaches may not have required sophisticated espionage tools, but rather exploited basic gaps in surveillance or access control, potentially prompting a review of security protocols at U.S. installations in Japan.