Search and rescue efforts are under way in coordination with local authorities, the Navy said.
Initial reports indicate the warship sustained damage to its port side aft.
The warship is named after John S. McCain, Sr., and John S. McCain, Jr., both Admirals in the U.S. Navy, and the grandfather and father, respectively, of the Arizona senator.
The ship is based at the fleet’s homeport of Yokosuka, Japan. It was commissioned in 1994 and has a crew of 23 officers, 24 chief petty officers and 291 enlisted sailors, according to the Navy’s website.
The Alnic MC, the merchant vessel USS John S. McCain collided with, is a 600-foot oil and chemical tanker.
This crash came days after the top three leaders aboard the USS Fitzgerald were relieved of command. That warship was damaged badly in a collision off the coast of Japan that killed seven sailors in June. One of its compartments flooded in about 90 seconds.
The USS John S. McCain sailed by contested man-made islands in the South China Sea earlier this month, drawing China’s “strong dissatisfaction.”
Sen. McCain tweeted Sunday night he and his wife, Cindy, were keeping the sailors in their prayers. He’d recently visited the warship in Vietnam.
This marked the fourth mishap for U.S. Navy ships in the Pacific since February.
Aside from the USS McCain and USS Fitgerald incidents, the Navy cruiser USS Antietam ran aground dumping over 1,000 gallons of oil in Tokyo Bay in February. In May, another cruiser, USS Lake Champlain, hit a South Korean fishing vessel.