A Japanese naval vessel has collided with a fishing boat east of Tokyo, leaving two fishermen missing.
A search is underway for the two missing fishermen
The Atago destroyer hit the Seitoku Maru fishing boat early on Tuesday off Chiba prefecture's Nojimazaki Cape, splitting the boat in two.
Coastguard ships and helicopters were searching for the missing fishermen, officials said.
The Atago is one of several Japanese navy ships equipped with the high-tech Aegis radar tracking system.
"It is extremely regrettable that this sort of accident has happened," Defence Minister Shigeru Ishiba told journalists.
"We must do all we can to search for and save the missing men and find out what caused it as soon as possible."
The two men, 58-year-old Haruo Kichisei and his son Tetsuhiro, had been out fishing for tuna, officials said.
It was the first serious accident involving a navy vessel and a civilian ship since a submarine and a fishing boat collided in Tokyo Bay in 1988, killing 30, Kyodo news agency said.
The Atago, the newest of Japan's Aegis-equipped vessels, was on its way back to the Yokosuka naval base from a training exercise in Hawaii when the incident occurred.
It and other vessels are key to Japan's missile defence shield, aimed at North Korea.
In December, a similar vessel armed with a Standard-3 missile defence system shot down a mock ballistic missile launched from a US base in Hawaii.