President Donald Trump sent a letter Thursday to the oldest-living survivor of the Pearl Harbor attack to wish him on his birthday.  Ray Chavez, a Poway, California, man turned 105 on March 11.

Trump's letter was tweeted by his Press Secretary Sean Spicer. The president wrote "keep going!" beside his signature at the end of the letter. He began by wishing Chavez a happy birthday and wrote: "I also join your many admirers in thanking you for your service to the United States of America. As the oldest living survivor of Pearl Harbor, your remarkable story is treasured by our nation, and the sacrifices you made in service to our country should fill you with tremendous pride."

Towards the end of the letter, Trump also thanked Chavez for his service, saying: "Melania and I want to join your friends and loved ones in honoring and thanking you for your service to our great nation. Our best wishes for health and happiness in the coming year."

Chavez celebrated his birthday Saturday at the USS Midway Aircraft Carrier Museum in San Diego.

"I feel very good every day, we don't live forever, so it doesn't bother me not one bit,” Chavez told CBS 8 News.

During the Pearl Harbor attack on Dec. 7, 1941, Chavez was a among the crew on a U.S. navy ship, the coastal minesweeper USS Condor, which was the first one to spot a periscope popping out of a Japanese midget submarine. The submarine was sunk by a destroyer on patrol nearby, while it was trying to get into the harbor. Chavez was off-duty when the Japanese air forces started attacking the harbor, but was called back to duty and remained there for a week. He later served as a quartermaster on a troop transport.

Read: Pearl Harbor Attack Remembered After 71 Years

The Pearl Harbor attack was the deadliest military attack on a U.S. naval base, an act that led to the country joining World War II. Bombings by Japanese forces killed 68 civilians and 2,335 military personnel, according to the Pearl Harbor Visitors Bureau. A large battleship, the USS Arizona, was completely destroyed and sunk by an 1,800 pound bomb, killing 1,177 people onboard. Another 300 aircraft and 20 naval vessels were also destroyed.