TOKYO -- A Japanese tug boat lost propulsion and drifted into a U.S. Navy guided-missile destroyer during a towing exercise Saturday, the Navy said.

The USS Benfold sustained minimal damage, including scrapes on its side, the Navy said in a statement. No one was injured on either vessel. The commercial tug boat was being towed to a port in Yokosuka, the home of the Navy's Japan-based 7th Fleet.

The collision occurred in Sagami Bay, which is southwest of Tokyo. The Navy said the Benfold remained at sea under its own power, and that the incident would be investigated.

Get Breaking News Delivered to Your Inbox

The 7th Fleet has had two fatal accidents in Asian waters this year, leaving 17 sailors dead and prompting the dismissal of eight top Navy officers, including the 7th Fleet commander.

The USS John S. McCain and an oil tanker collided near Singapore in August, leaving 10 U.S. sailors dead. Seven sailors died in June when the USS Fitzgerald and a container ship collided off Japan.

The Navy has concluded that the collisions were avoidable and resulted from widespread failures by the crews and commanders, who didn't quickly recognize and respond to unfolding emergencies. A Navy report recommended numerous changes to address the problems, ranging from improved training to increasing sleep and stress management for sailors.