TOKYO — U.S. and Japanese officials said they’re investigating the source of radio signals that disrupted an airport guidance system at Haneda International Airport on Monday morning, delaying 195 flights up to 91 minutes.

Japan’s Ministry of Land, Infrastructure and Transport confirmed Tuesday that the system that gauges altitude for descending planes was disrupted by signals coming from the direction of Yokosuka, a city that’s also home to a major U.S. Navy base.

Similar signals also may have disrupted operations three times within about a year.

Officials from both countries said they are unsure what caused this week’s signals.

“The source of the radio which interfered with an aircraft guidance system at Haneda International Airport Monday is yet to be identified,” said Yoshihiro Hayashi, an official of the ministry’s Civil Aviation Bureau, which oversees Japanese commercial airports. “It was found that the radio waves were transmitted from Yokosuka.”

He said radio interference caused the guidance system to malfunction from 7:03 to 10:30 a.m.

Lt. Gen. Bruce Wright, commander of U.S. Forces, Japan, responded to media inquiries Tuesday in a news release.

“Having seen the news reports and having been briefed on the incident at Haneda airport, I can assure you that U.S. Forces in Japan take very seriously any incident which may impact the safe navigation of aircraft,” Wright said in the news release.

“For many years, USFJ has coordinated these issues very closely with our counterparts in the Ministry of Land, Infrastructure & Transportation as well as in the Joint Civil Aeronautics Board,” he said. “We are as determined as ever to ensure incidents like this are properly investigated. I assure you that USFJ will investigate the cause of this interference and will share any information we discover with our counterparts.”

Hayashi said the first such incident occurred in October 2004 and the second was Oct. 10.

“It is highly possible that the source of the radio waves in the two cases this month was from the military facility” at Yokosuka, he said.

Air Force Maj. Richelle Dowdell, a U.S. Forces Japan spokeswoman, said nothing indicates the U.S. Navy caused the disruption but the Navy is “reviewing all shipboard operations to determine what exactly happened.”

Hayashi said such radio frequencies in Japan are limited to specific organizations, such as the Japanese Self Defense forces. The ministry Tuesday asked both the Self Defense Agency and U.S. Forces Japan to remember the radio frequency used at the airport and avoid disrupting it, he said.

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